The invention concerns a rock breaking device (10) comprising a striking cell (12) having at least one actuation chamber (14), a striking piston (16), and a hydraulic circuit. The hydraulic circuit comprises a hydraulic supply source having a high pressure circuit (17) and a low pressure circuit (18), and an actuator (20) configured to connect the high pressure circuit (17) or the low pressure circuit (18) to the actuation chamber (14) so as to move the piston in translation in the striking cell (12) in a normal movement area of which the limits are variable depending on the pressure difference between the high pressure circuit (17) and the low pressure circuit (18). The striking cell (12) comprises depressurising means configured to control the establishment of hydraulic communication between the high pressure circuit (17) and the low pressure circuit (18) when the striking piston (16) exits a predefined movement area.