To provide an optical module, an optical wiring board, and a method for manufacturing an optical module that provide the two-dimensional freedom degree of the joint portion between the optical module and the optical fiber even through the OBO method is applied to an optical module mounted via WLP. The optical module includes a board, a plurality of optical input-output portions that change a travel direction of light traveling substantially orthogonally to the board to a direction substantially parallel to the board and change a travel direction of the light traveling substantially parallel to the board to a direction substantially orthogonal to the board, one or more optical waveguides that optically connect the optical input-output portions to each other, and a lid that is attached to the board so as to include the optical input-output portions and the one or more optical waveguides, in which the lid has one or more reflection mirrors that change a travel direction of the light traveling from an outside of a side surface of the lid to an inside of the side surface so as to be directed to the optical input-output portions and change a travel direction of the light output from the optical input-output portions so as to be directed from the inside of the side surface of the lid to the outside of the side surface.