diff --git a/packages/backend/src/GlobalModule.ts b/packages/backend/src/GlobalModule.ts
index a2c834a740..55cf77ea83 100644
--- a/packages/backend/src/GlobalModule.ts
+++ b/packages/backend/src/GlobalModule.ts
@@ -31,16 +31,17 @@ const $config: Provider = {
 
 const $db: Provider = {
 	provide: DI.db,
-	useFactory: async (config) => {
+	useFactory: async (config: Config, loggerService: LoggerService) => {
+		const dbLogger = loggerService.getLogger('db');
 		try {
-			const db = createPostgresDataSource(config);
+			const db = createPostgresDataSource(config, dbLogger);
 			return await db.initialize();
 		} catch (e) {
-			console.error('failed to initialize database connection', e);
+			dbLogger.error('failed to initialize database connection', { e });
 			throw e;
 		}
 	},
-	inject: [DI.config],
+	inject: [DI.config, LoggerService],
 };
 
 const $meilisearch: Provider = {
diff --git a/packages/backend/src/postgres.ts b/packages/backend/src/postgres.ts
index 45caec54ce..01f5f0d19c 100644
--- a/packages/backend/src/postgres.ts
+++ b/packages/backend/src/postgres.ts
@@ -9,7 +9,7 @@ import { DataSource, Logger, type QueryRunner } from 'typeorm';
 import * as highlight from 'cli-highlight';
 import { entities as charts } from '@/core/chart/entities.js';
 import { Config } from '@/config.js';
-import MisskeyLogger from '@/logger.js';
+import MisskeyLogger, { type Data } from '@/logger.js';
 import { bindThis } from '@/decorators.js';
 
 import { MiAbuseUserReport } from '@/models/AbuseUserReport.js';
@@ -95,12 +95,6 @@ import { SkApInboxLog } from '@/models/SkApInboxLog.js';
 
 pg.types.setTypeParser(20, Number);
 
-export const dbLogger = new MisskeyLogger('db');
-
-const sqlLogger = dbLogger.createSubLogger('sql', 'gray');
-const sqlMigrateLogger = sqlLogger.createSubLogger('migrate');
-const sqlSchemaLogger = sqlLogger.createSubLogger('schema');
-
 export type LoggerProps = {
 	disableQueryTruncation?: boolean;
 	enableQueryLogging?: boolean;
@@ -118,16 +112,26 @@ function truncateSql(sql: string) {
 	return sql.length > 100 ? `${sql.substring(0, 100)} [truncated]` : sql;
 }
 
-function stringifyParameter(param: any) {
+function stringifyParameter(param: unknown): string {
 	if (param instanceof Date) {
 		return param.toISOString();
 	} else {
-		return param;
+		return String(param);
 	}
 }
 
-class MyCustomLogger implements Logger {
-	constructor(private props: LoggerProps = {}) {
+class TypeORMLogger implements Logger {
+	private readonly sqlLogger: MisskeyLogger;
+	private readonly sqlMigrateLogger: MisskeyLogger;
+	private readonly sqlSchemaLogger: MisskeyLogger;
+
+	constructor(
+		private readonly props: LoggerProps = {},
+		dbLogger: MisskeyLogger,
+	) {
+		this.sqlLogger = dbLogger.createSubLogger('sql', 'gray');
+		this.sqlLogger.createSubLogger('migrate');
+		this.sqlLogger.createSubLogger('schema');
 	}
 
 	@bindThis
@@ -143,9 +147,9 @@ class MyCustomLogger implements Logger {
 	}
 
 	@bindThis
-	private transformParameters(parameters?: any[]) {
+	private transformParameters(parameters?: unknown[]): Data | undefined {
 		if (this.props.enableQueryParamLogging && parameters && parameters.length > 0) {
-			return parameters.reduce((params, p, i) => {
+			return parameters.reduce((params: Record<string, string>, p, i) => {
 				params[`$${i + 1}`] = stringifyParameter(p);
 				return params;
 			}, {} as Record<string, string>);
@@ -155,37 +159,37 @@ class MyCustomLogger implements Logger {
 	}
 
 	@bindThis
-	public logQuery(query: string, parameters?: any[], queryRunner?: QueryRunner) {
+	public logQuery(query: string, parameters?: unknown[], queryRunner?: QueryRunner) {
 		if (!this.props.enableQueryLogging) return;
 
 		const prefix = (this.props.printReplicationMode && queryRunner)
 			? `[${queryRunner.getReplicationMode()}] `
 			: undefined;
 		const transformed = this.transformQueryLog(query, { prefix });
-		sqlLogger.debug(`Query run: ${transformed}`, this.transformParameters(parameters));
+		this.sqlLogger.debug(`Query run: ${transformed}`, this.transformParameters(parameters));
 	}
 
 	@bindThis
-	public logQueryError(error: string, query: string, parameters?: any[], queryRunner?: QueryRunner) {
+	public logQueryError(error: string, query: string, parameters?: unknown[], queryRunner?: QueryRunner) {
 		const prefix = (this.props.printReplicationMode && queryRunner)
 			? `[${queryRunner.getReplicationMode()}] `
 			: undefined;
 		const transformed = this.transformQueryLog(query, { prefix });
-		sqlLogger.error(`Query error (${error}): ${transformed}`, this.transformParameters(parameters));
+		this.sqlLogger.error(`Query error (${error}): ${transformed}`, this.transformParameters(parameters));
 	}
 
 	@bindThis
-	public logQuerySlow(time: number, query: string, parameters?: any[], queryRunner?: QueryRunner) {
+	public logQuerySlow(time: number, query: string, parameters?: unknown[], queryRunner?: QueryRunner) {
 		const prefix = (this.props.printReplicationMode && queryRunner)
 			? `[${queryRunner.getReplicationMode()}] `
 			: undefined;
 		const transformed = this.transformQueryLog(query, { prefix });
-		sqlLogger.warn(`Query is slow (${time}ms): ${transformed}`, this.transformParameters(parameters));
+		this.sqlLogger.warn(`Query is slow (${time}ms): ${transformed}`, this.transformParameters(parameters));
 	}
 
 	@bindThis
 	public logSchemaBuild(message: string) {
-		sqlSchemaLogger.debug(message);
+		this.sqlSchemaLogger.debug(message);
 	}
 
 	@bindThis
@@ -193,18 +197,18 @@ class MyCustomLogger implements Logger {
 		switch (level) {
 			case 'log':
 			case 'info': {
-				sqlLogger.info(message);
+				this.sqlLogger.info(message);
 				break;
 			}
 			case 'warn': {
-				sqlLogger.warn(message);
+				this.sqlLogger.warn(message);
 			}
 		}
 	}
 
 	@bindThis
 	public logMigration(message: string) {
-		sqlMigrateLogger.debug(message);
+		this.sqlMigrateLogger.debug(message);
 	}
 }
 
@@ -294,7 +298,7 @@ export const entities = [
 
 const log = process.env.NODE_ENV !== 'production';
 
-export function createPostgresDataSource(config: Config) {
+export function createPostgresDataSource(config: Config, dbLogger: MisskeyLogger) {
 	return new DataSource({
 		type: 'postgres',
 		host: config.db.host,
@@ -315,13 +319,13 @@ export function createPostgresDataSource(config: Config) {
 					password: config.db.pass,
 					database: config.db.db,
 				},
-				slaves: config.dbSlaves!.map(rep => ({
+				slaves: config.dbSlaves?.map(rep => ({
 					host: rep.host,
 					port: rep.port,
 					username: rep.user,
 					password: rep.pass,
 					database: rep.db,
-				})),
+				})) ?? [],
 			},
 		} : {}),
 		synchronize: process.env.NODE_ENV === 'test',
@@ -334,12 +338,12 @@ export function createPostgresDataSource(config: Config) {
 			},
 		} : false,
 		logging: log,
-		logger: new MyCustomLogger({
+		logger: new TypeORMLogger({
 			disableQueryTruncation: config.logging?.sql?.disableQueryTruncation,
 			enableQueryLogging: log,
 			enableQueryParamLogging: config.logging?.sql?.enableQueryParamLogging,
 			printReplicationMode: !!config.dbReplications,
-		}),
+		}, dbLogger),
 		maxQueryExecutionTime: config.db.slowQueryThreshold,
 		entities: entities,
 		migrations: ['../../migration/*.js'],