The inclination sensor (A1) according to the present invention includes a pair of light receiving elements (4A, 4B), a light emitting element (5) for directing light to the light receiving elements (4A, 4B) and a case (2) including a space (20) for accommodating a rolling member (6). The space (20) is configured to cause the rolling member (6) to be located at a pair of light shielding positions at which the rolling member overlaps the light receiving elements (4A, 4B) or a neutral position at which the rolling member does not overlap either of the light receiving elements (4A, 4B). The light receiving elements (4A, 4B) and the light emitting element (5) are mounted on a substrate (1) attached to the case (2) at a surface facing the space (20). A plurality of surface-mounting terminals (7a, 7b, 7c) are provided on a surface of the substrate (1) which is opposite from the surface on which the light receiving elements (4A, 4B) and the light emitting element (5) are mounted.