PURPOSE: To improve productivity in mass production and attain very low cost by rotatably supporting rams in the upper and lower parts of each pressurized mechanism and rotating at least a ram of the upper and lower rams around a shaft while a plurality of the pressurized mechanisms are arranged along heaters.

CONSTITUTION: At the time of hot press treatment an electric motor is actuated and each lower ram is rotated around a shaft. A formwork 24 and upper rams are integratedly rotated with the lower rams by mutual friction torque because the lower rams are rotated. The upper rams are rotated together with the rotary shaft rotatably supported on bearings. Thus, the whole side faces of specimens in the formwork 24 are uniformly faced to nearby heaters 6, and so the specimens are uniformly heated in the uniform distribution of temperature. After a prescribed treating time passes, the upper rams are raised to stop a pressurized condition, and heating by the heaters 6 is stopped. Therefore, a plurality of specimens are treated in a heating chamber.