A connection device configured to connect an optical fiber serving as a connection destination and an optical fiber that is a multi-core fiber serving as a connection source using an optical waveguide substrate, the connection device comprising: an end surface image acquisition part configured to acquire at least an image of a connection surface of a first fiber fixing part that is to be connected to a first end of the optical waveguide substrate and to which the optical fiber serving as a connection source is fixed without having undergone any rotation alignment; a coordinate derivation part configured to acquire, from the image of the connection surface acquired by the end surface image acquisition part, coordinates of a center position of a core of the optical fiber exposed on the connection surface of the first fiber fixing part; an optical waveguide formation part configured to inscribe, based on the coordinates acquired by the coordinate derivation part, an optical waveguide connecting the core of the optical fiber serving as a connection source to a core of the optical fiber serving as a connection destination in the optical waveguide substrate along a desired path extending from the first end to a second end of the optical waveguide substrate; and a connection part configured to connect the connection surface of the first fiber fixing part to the first end of the optical waveguide substrate and to connect a connection surface of a second fiber fixing part to which the optical fiber serving as a connection destination is fixed to the second end, wherein the optical fiber serving as a connection source and the optical waveguide substrate are fixedly connected with an adhesive or through fusion by electrical discharge. an end surface image acquisition part configured to acquire at least an image of a connection surface of a first fiber fixing part that is to be connected to a first end of the optical waveguide substrate and to which the optical fiber serving as a connection source is fixed without having undergone any rotation alignment; a coordinate derivation part configured to acquire, from the image of the connection surface acquired by the end surface image acquisition part, coordinates of a center position of a core of the optical fiber exposed on the connection surface of the first fiber fixing part; an optical waveguide formation part configured to inscribe, based on the coordinates acquired by the coordinate derivation part, an optical waveguide connecting the core of the optical fiber serving as a connection source to a core of the optical fiber serving as a connection destination in the optical waveguide substrate along a desired path extending from the first end to a second end of the optical waveguide substrate; and a connection part configured to connect the connection surface of the first fiber fixing part to the first end of the optical waveguide substrate and to connect a connection surface of a second fiber fixing part to which the optical fiber serving as a connection destination is fixed to the second end, wherein the optical fiber serving as a connection source and the optical waveguide substrate are fixedly connected with an adhesive or through fusion by electrical discharge.