To provide a pressure pulsation reducer capable of reducing pressure pulsation of pressure oil discharged from one discharge pressure port of a hydraulic pump and of reducing noise accompanied by the pressure pulsation.

Pressure oil discharged from the pump discharge pressure port (21) is introduced to a first pressure chamber (7) via an oil passage (3) and to a second pressure chamber (8) via a second oil passage from an oil passage (33) to a pipe line (35). Pulsation of the pressure oil introduced to the second pressure chamber (8) can be set in a state of the opposite phase to that of pulsation of the pressure oil introduced to the first pressure chamber (7), by the length of the second oil passage. A free piston (6) defining the first pressure chamber (7) and the second pressure chamber (8) is resonated and operated by the pulsation of the pressure oil introduced to each of the pressure chambers (7), (8), and promptly absorbs and alleviates the pulsation of pressure oil inside the oil passage (33) communicated with the first pressure chamber (7) by increasing/reducing the volume of the first pressure chamber (7). As a result, the pressure pulsation can be smoothed.