<p>[PROBLEMS] To hold a driver bit firmly to reduce its play when it is driven and rotated. [MEANS FOR SOLVING PROBLEMS] An electric driver (10) has a bit holder (14) for receiving and firmly holding a shaft of a driver bit (12) and a housing (18) having a through-hole (16) for receiving the bit holder (14) and holding it so as to be rotatable about its axis and slidable in the direction of the axis. The driver bit is firmly held by setting the driver bit as above in the through-hole (16) of a housing.</p>
