An optical waveguide module includes an optical waveguide sheet including multiple optical waveguides, and a light-emitting device and a light-receiving device each positioned over a surface of the optical waveguide sheet. At least one of the optical waveguides includes a first mirror, a second mirror, and a slit. The first mirror is configured to reflect light entering the corresponding optical waveguide from its first end to the light-receiving device or to reflect light emitted from the light-emitting device toward the first end of the corresponding optical waveguide. The second mirror is configured to reflect light entering the corresponding optical waveguide from its second end toward the surface of the optical waveguide sheet. The slit is provided between the second mirror and the second end of the corresponding optical waveguide. The corresponding optical waveguide is discontinuous across the slit.