Short answer. No. Labor Code Article 285 lets you end your employment without just cause simply by serving written notice on your employer at least one month in advance, with no requirement to state a reason. You would only need a specific just cause if you want to resign without giving that notice.
What the law says
An employee may terminate without just cause the employee-employer relationship by serving a written notice on the employer at least one (1) month in advance.
Labor Code, Article 285 — Resignation By The Employee. Read the full provision →
What the ordinary resignation path requires
Article 285 opens with the route almost everyone uses: an employee may terminate without just cause the employee-employer relationship by serving a written notice on the employer at least one (1) month in advance. Notice the phrase "without just cause" — the article itself contemplates resigning for no legally specified reason at all, so long as the written notice is given a month ahead. Nothing in that sentence asks you to justify the decision.
Why no explanation is built into this path
The article conditions this route on the notice period, not on the content of your reasoning. It does not require the notice to state why you are leaving, list an acceptable cause, or satisfy your employer that your reasons are good ones. As far as this provision is concerned, serving the written notice on time is what completes your side of the requirement.
When a reason actually becomes relevant
A reason only matters under this article if you want to skip the one-month notice altogether. The article separately lists specific just causes — serious insult, inhuman and unbearable treatment, a crime committed against you or your immediate family, or an analogous cause — that let you end the relationship without serving any notice at all. That is a different, narrower path from the ordinary one, and it is the only place in this article where your reason for leaving does the work.
What this means for how you resign
If you are simply resigning and giving the full month's notice, you are not obligated by this article to explain yourself, though many workplaces will still ask as a matter of courtesy or internal policy, which is separate from the legal requirement. Keep a copy of your written notice and the date you submitted it, since that is what actually satisfies Article 285 on the ordinary path.
What skipping the notice altogether can cost you
The article's flexibility about your reasons is not the same as flexibility about the notice itself. If you leave without serving the month's notice and without one of the specific just causes that excuses it, the employer on whom no notice was served may hold you liable for damages. So the choice this article actually gives you is not between explaining and not explaining — it is between giving the notice, whatever your reason, or having a recognized just cause that lets you skip it.