To provide a ceiling board for a bathroom unit facilitating the duct connection and inspection of a ventilation fan even when the ventilation fan or the like is installed on the back face of the bathroom unit.

A first ceiling board 1 having a flat section on which a functional section 11 such as the ventilation fan can be installed on the back face side of a ceiling and a second ceiling board 2 fixed apart by the prescribed height or above from the first ceiling board 1 are arranged via a third ceiling board 3 having a removable nearly vertical face to form this ceiling board for the bathroom unit. The connecting work of the functional section 11 and a duct 12 is facilitated by removing the third ceiling board 3 even when the second ceiling board 2 is located at a position near a building skeleton 6.