A safety switch comprising: a sensor main body; and an actuator, wherein the sensor main body comprises: a detection unit configured to detect the actuator when the actuator is disposed at a predetermined position with respect to the sensor main body; and a light projection unit configured to project light in accordance with a detection result of the detection unit, and wherein the actuator comprises: a light emitting unit configured to emit visible light in response to reception of the light projected by the light projection unit, the light emitting unit being formed of a light transmissive member, wherein the actuator comprises: a light guiding unit formed of the light transmissive member and configured to guide the light from the sensor main body to the light emitting unit; and a non-light-transmissive member surrounding an outer periphery of the light guiding unit, wherein the light emitting unit has an outer peripheral surface and an inner peripheral surface, wherein the outer peripheral surface faces, on an outer side of the inner peripheral surface, an outside of the actuator on a non-facing side that is a side opposite to the sensor main body, wherein the inner peripheral surface, on an inner side of the outer peripheral surface, faces the outside of the actuator on the non-facing side, wherein a diameter of the outer peripheral surface is reduced from a facing side facing the sensor main body toward the non-facing side so as to spread and diffuse the light through the light guiding unit, and/or a diameter of the inner peripheral surface increases from the facing side facing the sensor main body toward the non-facing side so as to diffuse the light guided through the light guiding unit in a center line of the actuator. a sensor main body; and an actuator, wherein the sensor main body comprises: a detection unit configured to detect the actuator when the actuator is disposed at a predetermined position with respect to the sensor main body; and a light projection unit configured to project light in accordance with a detection result of the detection unit, and a detection unit configured to detect the actuator when the actuator is disposed at a predetermined position with respect to the sensor main body; and a light projection unit configured to project light in accordance with a detection result of the detection unit, and wherein the actuator comprises: a light emitting unit configured to emit visible light in response to reception of the light projected by the light projection unit, the light emitting unit being formed of a light transmissive member, wherein the actuator comprises: a light guiding unit formed of the light transmissive member and configured to guide the light from the sensor main body to the light emitting unit; and a non-light-transmissive member surrounding an outer periphery of the light guiding unit, a light guiding unit formed of the light transmissive member and configured to guide the light from the sensor main body to the light emitting unit; and a non-light-transmissive member surrounding an outer periphery of the light guiding unit, wherein the light emitting unit has an outer peripheral surface and an inner peripheral surface, wherein the outer peripheral surface faces, on an outer side of the inner peripheral surface, an outside of the actuator on a non-facing side that is a side opposite to the sensor main body, wherein the inner peripheral surface, on an inner side of the outer peripheral surface, faces the outside of the actuator on the non-facing side, wherein a diameter of the outer peripheral surface is reduced from a facing side facing the sensor main body toward the non-facing side so as to spread and diffuse the light through the light guiding unit, and/or a diameter of the inner peripheral surface increases from the facing side facing the sensor main body toward the non-facing side so as to diffuse the light guided through the light guiding unit in a center line of the actuator.