Article 27 (Written Notice of Grounds, etc. for Dismissal), Labor Standards Act, as last amended by Act No. 12325, Jan. 21, 2014

An employer shall give a written notice for a dismissal stating the date and reason of dismissal. If an employer does not comply with the process, the dismissal becomes invalid.
Where an employer has given a worker an advance notice of dismissal under Article 26 in writing, stating grounds and timing for dismissal, the employer shall be deemed to have given notification.

*Labor Standards Act

Article 27 (Written Notice of Grounds, etc. for Dismissal)(1) When an employer intends to dismiss a worker, he/she shall notify the worker in writing of grounds and timing for the dismissal.

(2) The dismissal of a worker shall become effective only upon a written notice pursuant to paragraph (1).

(3) Where an employer has given a worker an advance notice of dismissal under Article 26 in writing, stating grounds and timing for dismissal, the employer shall be deemed to have given notification under paragraph (1).