Provided is an electrooptic conversion module, which can replace electronic parts more economically in case a malfunction occurs or in case an improvement is needed. In the electrooptic conversion module (1), a plurality of split units such as an optical signal transmit/receive unit (201) for converting an electric signal inputted into an optical signal to output the converted signal to the optical waveguide (2), an amplifying unit (202) and a communication control unit (203) are so fitted and retained in a fitting unit (120) to be connected with a cover member (111) exposed to the outside, that the terminal portions in the fitting portion (120) and the electrode portions of those split units contact with each other.