Abstract: A chuck for a tool, particularly a drilling tool has a shaft receivable in a machine spindle, a sleeve arranged for receiving a fast exchange insert with a tool or directly a tool, a longitudinal compensation device connecting the sleeve with the shaft and reacting to a relative axial displacement of the shaft and the sleeve, a signal device provided with a current source, a signal transmitter and a switch which is axially displaceable between the shaft and the sleeve and arranged in a current supply circuit of the signal transmitter, at least a part of which transmitter is arranged outside and peripherally of the shaft, and an outer ring holder which surrounds the shaft and carries the signal device together with the current source, the signal transmitter and the switch.