A filter apparatus capable of releasing air from a filter body, comprising a filter body held by a holder. The filter body includes a fluid inlet and a fluid outlet. The filter body is disposed in the holder so as to rotate around an axis of rotation that passes through the fluid inlet. The holder includes a front panel. The front panel comprises engaging portions, for temporarily engaging the fluid outlet at either an air releasing position or at a filtering position, and a fixing means for fixing the filter body at each position. The filter apparatus further includes means for rotating the filter body.