If you look at the entire workplace safety and health act and even in the first aid regulations, there are no requirements for a company to have an AED. 

So, MOM do not have any requirement for you to have an AED. 

However, if you look at SCDF national CERT standard, which most of you will fall into either one of the premise tier 1, 2 or 3 classification, there is a requirement for you to have at least 1 AED. 

This includes even in the lowest tier 3 classification, which will almost most workplaces in Singapore.

So in short, you need at least 1 AED in the company.