An electronic apparatus, comprising: a housing comprising: a bottom plate; and a plurality of side plates (10, 11, 12, 13) perpendicular to the bottom plate, at least one side plate (10, 11, 12, 13) among the plurality of side plates (10, 11, 12, 13) comprising a protrusion (21, 21A, 21B) protruding toward an inside of the housing; a first substrate parallel with the bottom plate; and at least one substrate module (6, 6A, 6B, 7, 7A, 8) standing upright on the first substrate, the at least one substrate module (6, 6A, 6B, 7, 7A, 8) comprising: a second substrate (50, 70, 71, 110); and a substrate fixing member (51, 73, 112) to which the second substrate (50, 70, 71, 110) is fixed, the substrate fixing member (51, 73, 112) comprising a hole (62, 62A, 62a, 62b, 102, 134, 151) engaged with the protrusion (21, 21A, 21B) of the at least one side plate (10, 11, 12, 13); wherein the first substrate comprises a first connector (33, 35, 36, 37, 38, 39, 40, 41), wherein the second substrate (50, 70, 71, 110) comprises a second connector (54, 76, 77, 78, 87, 114, 115, 116) connected to the first connector (33, 35, 36, 37, 38, 39, 40, 41), and wherein the hole (62, 62A, 62a, 62b, 102, 134, 151) comprises an abutting portion (63, 63A, 63a, 63b, 103, 135, 152) abutting on a side surface of the protrusion (21, 21A, 21B) with the first connector (33, 35, 36, 37, 38, 39, 40, 41) and the second connector (54, 76, 77, 78, 87, 114, 115, 116) connected to each other; and wherein with the abutting portion (63, 63A, 63a, 63b, 103, 135, 152) of the hole (62, 62A, 62a, 62b, 102, 134, 151) abutting on the side surface of the protrusion (21, 21A, 21B), the substrate fixing member (51, 73, 112) is fixed with a screw to the bottom plate and at least one side plate (10, 11, 12, 13) among the plurality of side plates (10, 11, 12, 13); wherein the hole (62, 62A, 62a, 62b, 102, 134, 151) has a width within which movement of the protrusion (21, 21A, 21B) in a direction perpendicular to the second substrate (50, 70, 71, 110) is restricted, and wherein the hole (62, 62A, 62a, 62b, 102, 134, 151) has a length greater than the width in a direction perpendicular to the first substrate. a housing comprising: a bottom plate; and a plurality of side plates (10, 11, 12, 13) perpendicular to the bottom plate, at least one side plate (10, 11, 12, 13) among the plurality of side plates (10, 11, 12, 13) comprising a protrusion (21, 21A, 21B) protruding toward an inside of the housing; a bottom plate; and a plurality of side plates (10, 11, 12, 13) perpendicular to the bottom plate, at least one side plate (10, 11, 12, 13) among the plurality of side plates (10, 11, 12, 13) comprising a protrusion (21, 21A, 21B) protruding toward an inside of the housing; a first substrate parallel with the bottom plate; and at least one substrate module (6, 6A, 6B, 7, 7A, 8) standing upright on the first substrate, the at least one substrate module (6, 6A, 6B, 7, 7A, 8) comprising: a second substrate (50, 70, 71, 110); and a substrate fixing member (51, 73, 112) to which the second substrate (50, 70, 71, 110) is fixed, the substrate fixing member (51, 73, 112) comprising a hole (62, 62A, 62a, 62b, 102, 134, 151) engaged with the protrusion (21, 21A, 21B) of the at least one side plate (10, 11, 12, 13); a second substrate (50, 70, 71, 110); and a substrate fixing member (51, 73, 112) to which the second substrate (50, 70, 71, 110) is fixed, the substrate fixing member (51, 73, 112) comprising a hole (62, 62A, 62a, 62b, 102, 134, 151) engaged with the protrusion (21, 21A, 21B) of the at least one side plate (10, 11, 12, 13); wherein the first substrate comprises a first connector (33, 35, 36, 37, 38, 39, 40, 41), wherein the second substrate (50, 70, 71, 110) comprises a second connector (54, 76, 77, 78, 87, 114, 115, 116) connected to the first connector (33, 35, 36, 37, 38, 39, 40, 41), and wherein the hole (62, 62A, 62a, 62b, 102, 134, 151) comprises an abutting portion (63, 63A, 63a, 63b, 103, 135, 152) abutting on a side surface of the protrusion (21, 21A, 21B) with the first connector (33, 35, 36, 37, 38, 39, 40, 41) and the second connector (54, 76, 77, 78, 87, 114, 115, 116) connected to each other; and wherein with the abutting portion (63, 63A, 63a, 63b, 103, 135, 152) of the hole (62, 62A, 62a, 62b, 102, 134, 151) abutting on the side surface of the protrusion (21, 21A, 21B), the substrate fixing member (51, 73, 112) is fixed with a screw to the bottom plate and at least one side plate (10, 11, 12, 13) among the plurality of side plates (10, 11, 12, 13); wherein the hole (62, 62A, 62a, 62b, 102, 134, 151) has a width within which movement of the protrusion (21, 21A, 21B) in a direction perpendicular to the second substrate (50, 70, 71, 110) is restricted, and wherein the hole (62, 62A, 62a, 62b, 102, 134, 151) has a length greater than the width in a direction perpendicular to the first substrate.