To detach a tire bead from a wheel rim without damaging a tire and to improve the efficiency of tire replacement work.

An extensible arm 5 approaching/separating from a rotation axis L1 of a turntable 4 is provided with an insertion implement 8 angularly displaceable around an angular displacement axis L2. The other end of an insertion implement body 7 is pressed by an insertion implement driving means 9 to angularly displace an insertion part 7 in a separating direction from the rotation axis L1 of the turntable 4, and the insertion part 7 is angularly displaced in an approaching direction to the rotation axis L1 by a spring energizing means 12.