An optical module comprising: a plurality of light source mounting parts, which each include a light source, a circuit board on which the light source is mounted, and a reinforcement plate attached to the circuit board to reinforce the circuit board, the circuit board being attached to a lateral surface (9A3) of a housing containing optical parts to let the optical module combine light from a plurality of light sources and irradiate a desired region with the combined light, a flange that is formed on the outer circumference of and to be substantially perpendicular to the lateral surface (9A3) of the housing to which the light source mounting parts are attached; and a first thermally conductive member that includes a first surface and a second surface, the first surface being thermally conductively connected to a surface of the reinforcement plate different from a surface of the reinforcement plate that is attached to the circuit board, the second surface of the first thermally conductive member being thermally conductively connected to the flange, wherein the first thermally conductive member has an inclined surface on the back side of the first surface, the inclined surface being formed along the first surface in such a manner that the thickness between the first surface and the inclined surface increases with a decrease in the distance to the second surface, a first thermal path is formed such that it conducts the heat of the light source from the circuit board to the lateral surface (9A3) of the housing via the reinforcement plate and the circuit board again, and a second thermal path is formed such that it conducts the heat of the light source from the circuit board to the flange of the housing via the reinforcement plate and the first thermally conductive member, and the circuit board, the reinforcement plate and the first surface of the first thermally conductive member extend along the lateral surface (9A3) of the housing. a plurality of light source mounting parts, which each include a light source, a circuit board on which the light source is mounted, and a reinforcement plate attached to the circuit board to reinforce the circuit board, the circuit board being attached to a lateral surface (9A3) of a housing containing optical parts to let the optical module combine light from a plurality of light sources and irradiate a desired region with the combined light, a flange that is formed on the outer circumference of and to be substantially perpendicular to the lateral surface (9A3) of the housing to which the light source mounting parts are attached; and a first thermally conductive member that includes a first surface and a second surface, the first surface being thermally conductively connected to a surface of the reinforcement plate different from a surface of the reinforcement plate that is attached to the circuit board, the second surface of the first thermally conductive member being thermally conductively connected to the flange, wherein the first thermally conductive member has an inclined surface on the back side of the first surface, the inclined surface being formed along the first surface in such a manner that the thickness between the first surface and the inclined surface increases with a decrease in the distance to the second surface, a first thermal path is formed such that it conducts the heat of the light source from the circuit board to the lateral surface (9A3) of the housing via the reinforcement plate and the circuit board again, and a second thermal path is formed such that it conducts the heat of the light source from the circuit board to the flange of the housing via the reinforcement plate and the first thermally conductive member, and the circuit board, the reinforcement plate and the first surface of the first thermally conductive member extend along the lateral surface (9A3) of the housing.