A telecentric optical apparatus comprising: a front-stage lens part that includes a first telecentric lens surface that is provided on an object side; a rear-stage lens part that includes a second telecentric lens surface that is provided on an image side and that shares a focus position (F1, F2) with the first telecentric lens surface; and an optical path trimming part that is provided to at least either one of the front-stage lens part or the rear-stage lens part and is positioned between the first telecentric lens surface and the second telecentric lens surface, in an outside region, which is located on a side further out than a light passing region having a center thereof located at the focus position (F1, F2), and that changes an optical path such that a light beam incident on the outside region is prevented from contributing to image formation, wherein the optical path trimming part is formed integrally with at least one of the first telecentric lens surface and the second telecentric lens surface; the telecentric optical apparatus further comprising: a fitting part that is provided between the front-stage lens part and the rear-stage lens part, the position of the fitting part corresponding to the position of the light passing region of the front stage lens part and rear-stage lens part, the fitting part comprising a concave part provided on one of the front-stage lens part and the rear-stage lens part and a convex part provided on the other of the front-stage lens part and the rear-stage lens part, wherein the concave part and convex part are fitted into each other to connect the front-stage lens part and the rear-stage lens part together by way of fitting. a front-stage lens part that includes a first telecentric lens surface that is provided on an object side; a rear-stage lens part that includes a second telecentric lens surface that is provided on an image side and that shares a focus position (F1, F2) with the first telecentric lens surface; and an optical path trimming part that is provided to at least either one of the front-stage lens part or the rear-stage lens part and is positioned between the first telecentric lens surface and the second telecentric lens surface, in an outside region, which is located on a side further out than a light passing region having a center thereof located at the focus position (F1, F2), and that changes an optical path such that a light beam incident on the outside region is prevented from contributing to image formation, wherein the optical path trimming part is formed integrally with at least one of the first telecentric lens surface and the second telecentric lens surface; the telecentric optical apparatus further comprising: a fitting part that is provided between the front-stage lens part and the rear-stage lens part, the position of the fitting part corresponding to the position of the light passing region of the front stage lens part and rear-stage lens part, the fitting part comprising a concave part provided on one of the front-stage lens part and the rear-stage lens part and a convex part provided on the other of the front-stage lens part and the rear-stage lens part, wherein the concave part and convex part are fitted into each other to connect the front-stage lens part and the rear-stage lens part together by way of fitting.