A first optical-electrical transmission connector being configured to be connected to a second optical-electrical transmission connector, the second optical-electrical transmission connector including an intermediate board on which are arranged: one or a plurality of optical devices which include at least one of a light-emitting device emitting light to one direction and a light-sensing device sensing light from the one direction, one or a plurality of second collimating lenses arranged in a light-passing region where light emitted from or entering into the one or the plurality of optical devices passes through, a second positioning section having a ring-shaped second inclined surface formed corresponding to surroundings of the one or the plurality of second collimating lenses when viewed from the one direction, and one or a plurality of second electrical transmission electrode pads formed corresponding to surroundings of the second inclined surface when viewed from the one direction, the first optical-electrical transmission connector comprising: a flexible board on which are arranged: one or a plurality of first collimating lenses facing the one or the plurality of second collimating lenses in the one direction when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector; a first positioning section formed corresponding to surroundings of the one or the plurality of first collimating lenses and having a ring-shaped first inclined surface, the first inclined surface coming into contact with the second inclined surface when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector; one or a plurality of light guides arranged corresponding to the focal points of the one or the plurality of first collimating lenses; and one or a plurality of first electrical transmission electrode pads formed corresponding to surroundings of the first inclined surface, and coming into contact) with the second electrical transmission electrode pad when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector. one or a plurality of optical devices which include at least one of a light-emitting device emitting light to one direction and a light-sensing device sensing light from the one direction, one or a plurality of second collimating lenses arranged in a light-passing region where light emitted from or entering into the one or the plurality of optical devices passes through, a second positioning section having a ring-shaped second inclined surface formed corresponding to surroundings of the one or the plurality of second collimating lenses when viewed from the one direction, and one or a plurality of second electrical transmission electrode pads formed corresponding to surroundings of the second inclined surface when viewed from the one direction, the first optical-electrical transmission connector comprising: a flexible board on which are arranged: one or a plurality of first collimating lenses facing the one or the plurality of second collimating lenses in the one direction when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector; a first positioning section formed corresponding to surroundings of the one or the plurality of first collimating lenses and having a ring-shaped first inclined surface, the first inclined surface coming into contact with the second inclined surface when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector; one or a plurality of light guides arranged corresponding to the focal points of the one or the plurality of first collimating lenses; and one or a plurality of first electrical transmission electrode pads formed corresponding to surroundings of the first inclined surface, and coming into contact) with the second electrical transmission electrode pad when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector. one or a plurality of first collimating lenses facing the one or the plurality of second collimating lenses in the one direction when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector; a first positioning section formed corresponding to surroundings of the one or the plurality of first collimating lenses and having a ring-shaped first inclined surface, the first inclined surface coming into contact with the second inclined surface when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector; one or a plurality of light guides arranged corresponding to the focal points of the one or the plurality of first collimating lenses; and one or a plurality of first electrical transmission electrode pads formed corresponding to surroundings of the first inclined surface, and coming into contact) with the second electrical transmission electrode pad when connecting the first optical-electrical transmission connector to the second optical-electrical transmission connector.