To provide a tool mounting device for a turning center that allows a rotating tool to be clamped/fixed using a shared clamp mechanism (8), and a turning tool (1B) to be clamped/fixed in an engaged/locked state in a turning center. In the turning center configured with the shared clamp mechanism (8), a cylinder device (9) acting as a drawbar drive device (9) of the clamp mechanism (8) has a first clamp position (b) and second clamp position (c) in relation to a release position (a); a rotation allowance gap (14) is maintained between the stopper (12) and the support unit (13) in the first clamp position (b) to specifically clamp/fix the rotating tool (1A); the reciprocating driver (11) is driven by an amount equal to the rotation allowance gap (14) in the second clamp position (c); and when the support unit (13) and the stopper (12) are brought into contact and a load is imposed, the stopper (12) is supported/stopped by the support unit (13), and the reciprocating driver (11) is engaged/locked by the wedge mechanism (18) in the position of the return blocking state in which the return of the drawbar (7) is blocked.