A cylinder portion is divided into a cylinder main body, and two side cylinders coupled to opposite ends of the cylinder main body. The cylinder main body is configured so that a sample-enclosing capsule in which a sample and a pressure medium are enclosed can be disposed inside the cylinder main body. Pistons for load transmission are disposed at opposite ends of the interior of the cylinder portion; and locking nuts are provided on the outer sides of the positions. The pistons are moved in an axial direction by screwing the locking nuts. With this configuration, a piston cylinder-type high-pressure generating device in which a cylinder having a small outer diameter is formed of a non-magnetic material can generate a high pressure while securing a sample space having a predetermined effective volume.