A hydraulic circuit construction for a power shift transmission having logical operation valves mounted on a pressure oil supply passage connecting a hydraulic clutch to a pressure oil source, the logical operation valves being operable to engage and disengage the hydraulic clutch by opening and closing the pressure oil supply passage in response to a switching operation of a change speed device connected upstream of and in series to the hydraulic clutch. The pressure oil supply passage has mounted thereon a pressure control device including a first valve mechanism, a second valve mechanism and an orifice parallel-connected to the pressure oil supply passage, and an accumulator is mounted between the pressure control device and the hydraulic clutch to assure a speedy and smooth operation of the hydraulic clutch.