In a fluid pressure apparatus, a packing includes an annular seal member made of an elastic material, and support rings made of a low-friction material, which are mounted on an outer circumference of the seal member. The seal member includes, on an outer circumference thereof, a sealing projection that contacts an inner surface of the slide hole. The support rings are disposed on both sides of the sealing projection, and protrude beyond the seal member in the axial direction. Outer circumferential surfaces of the support rings always contact the inner circumferential surface of the slide hole. When a transverse load does not act on a piston as a partitioning member, the inner circumferential surfaces of the support rings do not contact the outer circumference of the piston. When a transverse load acts on the piston, the inner circumferential surfaces of the support rings contact the outer circumference of the piston.