Abstract: Proposed is a rebar coupler including a housing formed by coupling a pair of housing bodies to each other and a plurality of coupling pieces positioned inside the housing and configured to fasten a rebar. The coupling piece includes an outer surface having a first protruding region, a second protruding region, and a first concaved region, and includes an inner surface having serrated protrusions configured to prevent the rebars from being moved in an opposite direction of an insertion direction. The housing body has concaved spaces such that symmetrical hollows are formed at the opposite sides of the housing, and rebar inlet ports are formed at opposite ends of the housing. A pair of the coupling pieces is positioned at the hollows such that the inner surfaces of the coupling pieces face each other, and the first end portions of the coupling pieces are configured to fasten the rebars.