Provided is a hot isostatic pressing device (HIP) (1) that enables prompt cooling in a processing chamber. The HIP device (1) is provided with the following: gas impermeable casings (3, 4); a heating unit (7); a high-pressure container (2); a heat accumulator (43) provided below a processing chamber; and a cooling promotion flow path (44). The casings (3, 4) are disposed so as to form the following: a first circulation flow (41) in which a pressure medium gas passes through an inner flow path (22) and an outer flow path (12) and then returns to the inner flow path (22); and a second circulation flow (42) in which the pressure medium gas which has branched off from the first circulation flow (41) performs heat exchange with an object-of-processing (W) in the processing chamber and then is fed back to the first circulation flow (41). In the cooling promotion flow path (44), the pressure medium gas that is in the second circulation flow (42) and that has performed heat exchange with the object-of-processing (W) is guided to the heat accumulator (43) and cooled by the heat accumulator (43) before the pressure medium gas merges with the first circulation flow (41).