A bulb-type lamp (1, 370) comprising: a light emitting module (3, 371) including a substrate on which at least one light emitting element is mounted; a cylindrically-shaped heat sink (7, 373) that allows dissipation of heat therefrom, the heat being generated by the at least one light emitting element emitting light; a base member attached to one end portion of the heat sink (7, 373); a circular plate-shaped mount member on a front surface of which the light emitting module is mounted, the mount member allowing conduction of the heat therefrom to the heat sink (7, 373) by an outer circumferential surface of the mount member being in contact with an inner circumferential surface of the other end portion of the heat sink (7, 373); a circuit that is housed in the heat sink and, upon receiving power via the base member, causes the at least one light emitting element to emit the light; a fraction S1/S2 satisfies a relationship 0.5 ≤S1/S2, where S1 denotes an area of a portion of the mount member that is in contact with the heat sink (7, 373), and S2 denotes an area of a portion of the mount member that is in contact with the substrate of the light emitting module (3, 371); characterized in that a circuit holder member is positioned inside the heat sink, with the circuit disposed inside the circuit holder member; an air space exists (i) between the circuit holder member and the heat sink, and/or (ii) between the circuit holder member and the mount member, and the circuit is isolated from the air space by the circuit holder member; and in that a ratio of a thickness of a portion of the mount member on which the light emitting module is mounted to an outer diameter of the mount member is at most 0.16. a light emitting module (3, 371) including a substrate on which at least one light emitting element is mounted; a cylindrically-shaped heat sink (7, 373) that allows dissipation of heat therefrom, the heat being generated by the at least one light emitting element emitting light; a base member attached to one end portion of the heat sink (7, 373); a circular plate-shaped mount member on a front surface of which the light emitting module is mounted, the mount member allowing conduction of the heat therefrom to the heat sink (7, 373) by an outer circumferential surface of the mount member being in contact with an inner circumferential surface of the other end portion of the heat sink (7, 373); a circuit that is housed in the heat sink and, upon receiving power via the base member, causes the at least one light emitting element to emit the light; a fraction S1/S2 satisfies a relationship 0.5 ≤S1/S2, where S1 denotes an area of a portion of the mount member that is in contact with the heat sink (7, 373), and S2 denotes an area of a portion of the mount member that is in contact with the substrate of the light emitting module (3, 371); characterized in that a circuit holder member is positioned inside the heat sink, with the circuit disposed inside the circuit holder member; an air space exists (i) between the circuit holder member and the heat sink, and/or (ii) between the circuit holder member and the mount member, and the circuit is isolated from the air space by the circuit holder member; and in that a ratio of a thickness of a portion of the mount member on which the light emitting module is mounted to an outer diameter of the mount member is at most 0.16.