The decision comes two weeks after three women sued Wal-Mart over its failure to carry the pill, reports The Associated Press.
They argued that state law requires pharmacies to provide all "commonly prescribed medicines."
The board sent a letter to Wal-Mart to notify the retail giant of its decision, said health department spokeswoman Donna Rheaume.
The company has until Thursday to say in writing that it intends to follow the new policy.
Wal-Mart spokesman Dan Fogleman said the company hadn't heard about the decision, but would comply with any order.
