A wafer grinding machine and a wafer grinding method are disclosed. A barrier (60) is arranged around a holding unit (29) to hold at least a wafer (40) with a film (11) attached on the front surface (41) thereof and with the back surface (42) thereof directed upward. The upper surface (61) of the barrier unit is ground to the position between the back surface of the wafer held by the holding unit and the boundary between the wafer and the film. Then, the wafer is ground while being held with the back surface thereof up by the holding unit. As a result, the film is prevented from coming off from the wafer at the time of grinding the back surface of the wafer. Further, when the wafer is ground, a fluid may be supplied into the gap between the barrier unit and the outer peripheral portion of the wafer held by the holding unit.