A substrate mounting structure includes: a substrate member including a substrate portion, the substrate portion having first and second surfaces opposite to each other in a thickness direction of the substrate portion, first to fourth edges, and a predetermined thickness in the thickness direction; a first mounting member on which the substrate member is placed; and a second mounting member attached to the first mounting member to hold the substrate member on the first mounting member. The first mounting member includes first, second, and third restricting portions abutting on the first edge, the second edge, and the second surface to restrict movement of the substrate member, respectively. The second mounting member includes fourth, fifth, and sixth restricting portions abutting on the third edge, the fourth edge, and the first surface to restrict movement of the substrate member.