Abstract: A device for transperineal biopsy with a movable arm of a robot, comprising: an ultrasound probe being mounted around a first axis; a surgical instrument with a needle, which is movable along a first trajectory; and a moving device comprising at least a first pair of arms facing one another and arranged around a first longitudinal axis of the ultrasound probe so as to move, preferably oscillate, around the axis along a second trajectory, in order to guide and support the needle at a free end of each guide arm; and a connection interface to connect the device to a movable arm of a robot and having an operating module, which comprises a plurality of actuators each to move a respective said ultrasound probe or said guide arms, and a separation module arranged on the operating module and configured to transmit the motion to the ultrasound probe or to the arms.