According to the connection device, the connection method, the optical connector manufacturing device, and the method for manufacturing an optical connector, rotation alignment of an MCF becomes unnecessary because an image of an end surface of the MCF to be connected is captured, the position of the core is located, and an optical waveguide is formed on a substrate so as to match the position. Thus, it is possible to solve the problem of increasing loss or complex connection work caused by rotational misalignment in association with rotation alignment.