Can I become a director in another company while I am already on EP (Employment Pass) for one company?

Yes, you can become a director in another company while you are on EP for a company. But you must seek the approval of your company and MOM (Ministry of Manpower) to do so.

The approval will be given only if the other company is related to the company in which you are working and the role of director in that company is incidental to your main work.

You can not take the role of director in some other unrelated company.