A bit mounting device (10; 30) includes a holder (12) that may be mounted to a spindle of the power tool or may be a part of the spindle. A bit push member (15) is disposed within a bit receiving hole (12b) that is formed in the holder (12) for receiving a tool bit (1). The movement of the operation member (20; 31) is transmitted to the bit push member (15) via a transmission mechanism (14, 15d, 20b; 14, 15d, 31b), so that the tool bit (1) is pushed in a removing direction from the bit receiving hole (12b) by the bit push member (15).