A printed circuit board is disclosed. A printed circuit board, which includes a first board part, a flexible board part which has one side coupled with the first board part and which includes an electrical wiring layer and an optical waveguide to transmit both electrical signals and optical signals, and a second board part coupled with the other side of the flexible board part, where the electrical wiring layer and the optical waveguide are disposed with a gap in-between, can provide greater bendability and reliability, by having the optical waveguide and electrical wiring layer separated with a gap in-between at the flexible portion of the board, and the optical waveguide can be manufactured with greater precision for even higher reliability, by having the optical waveguide manufactured separately and then inserted during the manufacturing process of the board.