In a joint section 3 of a piston ring 1, on a side surface 2a of a body 2, a first protrusion portion 13 and a first reception portion 14 are provided, on a side surface 2b of the body 2, a second protrusion portion 15 and a second reception portion 16 are provided, on an inner circumferential surface 2c side of the body 2, a first male portion 21 and a first female portion 22 are provided, and, on an outer circumferential surface 2d side of the body 2, a second male portion 23 and a second female portion 24 are provided. The first male portion 21 has an inclined surface 21b which faces the outer circumferential surface 2d side and is inclined with respect to a mating surface 21a with respect to the first female portion 22 so that a front end of the first male portion 21 tapers, and the second male portion 23 has an inclined surface 23b which faces the inner circumferential surface 2c side and is inclined with respect to a mating surface 23a with respect to the second female portion 24 so that a front end of the second male portion 23 tapers.