A light guide body aggregate substrate includes: a light-transmitting substrate having a main surface; a plurality of unit regions, wherein the plurality of unit regions are arranged one-dimensionally in one row extending in a first direction and a plurality of columns, or two-dimensionally in a plurality of rows extending in the first direction and a plurality of columns extending in a second direction, and wherein a light guide structure is located in each unit region; a marginal region; and a plurality of first alignment marks arranged in the first direction on the substrate in the marginal region, each first alignment mark being disposed at a position corresponding to a position in the first direction of a corresponding one of the plurality of columns of the plurality of unit regions extending in the second direction.