var sourcemaps = require('gulp-sourcemaps'); ← ★(1) gulp.task('css', function(){ return sass('./src/scss/', { style: 'expanded',// nested, compact, compressed, expanded sourcemap: true ← ★(2) }) .on('error', function(err){ console.error('Error!', err.message); }) .pipe(sourcemaps.write()) ← ★(3) .pipe(gulp.dest('./public/resources/css')); }); (1)で読み込んで (2)で sourcemap: true を設定して (3)で sourceMapp