There are many reasons you may need one, such as:
To start with it takes the responsibility off your shoulders. The company is now responsible for finding a good tenant, and keeping the property tenanted for as long as possible. Now, why is a property management company able to do this more effectively than you? Few reasons:
But having said that, is property management for everyone? Definitely not. If you are a hands-on landlord, and stay very close to your property and have the extra time to deal with tenanting and tenant management, then you can save a few extra bucks, doing so yourself.
For everyone else, hiring a property management firm, will in fact, increase the returns on your property investment by close to 20%, if not more.