Pressing device

A pressing device comprising:

• a pressure vessel;
• a piston body fitted into an inside of the pressure vessel movably in an insertion direction and an extraction direction relative to the pressure vessel;
• a piston seal provided in the piston body and configured to seal a gap between the piston body and the pressure vessel;
• a piston axial force information detection unit configured to detect piston axial force information pertaining to an axial force applied to the piston body in a movement direction of the piston body relative to the pressure vessel;
• a driving device configured to move the piston body relative to the pressure vessel;
• a friction information storage unit configured to store friction information pertaining to a frictional force between the piston seal and the pressure vessel when the piston body moves relative to the pressure vessel;
• and
• a drive control unit configured to control the driving device based on the piston axial force information detected by the piston axial force information detection unit, and the friction information stored in the friction information storage unit,
• wherein in a holding stroke for controlling a pressure inside the pressure vessel so as to be constantly held, the drive control unit controls the driving device so that the piston body performs a reciprocating motion relative to the pressure vessel.