NOVELTY - Hydraulic jet device includes water conduit made in the form of system of channels with inlet water intake holes, which are located symmetrically relative to its longitudinal axis, vertical side walls common for all channels and with curved walls which are horizontal in cross section of channels, forming nozzles converging in the flow direction and having the outlet holes for conversion of mechanical energy of the ship's rolling to hydraulic jet energy; at that, system contains two stages of energy conversion, which are located one after the other, each of the stages is made in the form of system of channels located one above the other in vertical longitudinal plane of the water conduit section and symmetrically relative to its longitudinal axis; at that, the first stage has two upper and lower external channels, at least two upper and lower internal channels, and one central channel, and the second stage has two upper and lower external channels and one central channel the input of which is interconnected with output of channels of the first stage; horizontal walls of channels are curved in longitudinal direction with plates, upper and lower external and internal channels of the first stage and upper and low external channels of the second stage are located opposite to each other, and inlet water intake hole of central channel is located in vertical plane perpendicular to longitudinal axis of water conduit; external walls of upper and lower external channels of the first and the second stages are concave relative to longitudinal axis of water conduit, upper and lower walls respectively of upper and lower internal channels of the first stage, which are common with lower and upper wall of upper and lower external channels of the first stage, as well as upper and lower walls of central channel of the second stage, which form lower and upper walls of external channels of the second stage are made of straight plates with inlet section which is convex relative to longitudinal axis of water conduit, and horizontal curved walls of central channel of the first stage are made of straight planes with the section concave relative to longitudinal water conduit axis and located on the side of inlet water intake hole and are at the same time the walls of upper and lower internal channels of the first stage; at that, at the input of the central channel between horizontal curved walls of central channel of the first stage there installed with possibility of being turned relative to its entering edge is horizontal plane plate the leading edge of which is taken forward and located before inlet water intake hole of central channel, at the output of the second stage there installed on water conduit is shell forming the channel divergent in the flow direction so that the second stage of water intake holes is formed above upper and under lower external channels, and in vertical side walls between rear edges of vertical side walls and front edges of vertical walls there made on the side of narrow inlet section of the shell are vertical slot-type holes.    USE - Power industry.    ADVANTAGE - Increasing efficiency of its use during conversion of wave energy to hydraulic jet energy, increasing use efficiency of hydraulic jet device at conversion of wave energy to hydraulic jet energy.