A liquid pressure circuit is provided in which connecting an accumulator (22) to a high pressure liquid path (Lh) by opening a cut-off valve (24a) and connecting a intake liquid path (Li) to the high pressure liquid path (Lh) by means of a switch valve (24b) enables a pump/motor (M) to be operated as a motor by liquid stored under pressure in the accumulator (22), connecting the accumulator (22) to the high pressure liquid path (Lh) by opening the cut-off valve (24a) and connecting the intake liquid path (Li) to a low pressure liquid path (Ll) by means of the switch valve (24b) enables the pump/motor (M) to be operated as a pump to thus store liquid of a tank (21) under pressure in the accumulator (22), and closing the cut-off valve (24a) and connecting the intake liquid path (Li) to the high pressure liquid path (Lh) by means of the switch valve (24b) enables the pump/motor (M) to rotate without load; it is therefore possible to switch between three circuits, that is, drive (motor operation), regeneration (pump operation), and neutral (load-free running) by a simple structure with a small number of components.