To provide a device capable of jetting a cleaning liquid at a substantially constant jet pressure continuously and efficiently without increasing the number of pollution sources.

In this device, the cleaning liquid is sent from a liquid pressure source 1 and jetted from a jet orifice 7. The device is characterized by being equipped with liquid sending pipes 2, 3, 4 starting from the pressure source 1, branching off in two directions, and meeting each other to extend to the orifice 7, a first booster 10 of a two-rod double-acting type connected between the branching point and the meeting point 5 of the feeding pipes and capable of boosting the liquid pressure in the branch pipes alternately, and a second booster 20 connected between the first booster 10 and the orifice 7 and operating in association with the operation of the first booster 10.