A door switch , comprising an actuator and a sensor , wherein the sensor is formed with a front surface (S1), a back surface (B1) and side surfaces (SD1) connecting the front surface (S1) and the back surface (B1), wherein the door switch is installed so that when a door is closed, the front surface (S1) of the sensor and an opposite surface (S2) of the actuator are in contact with or close to each other, and when the door is open, the front surface (S1) of the sensor and the opposite surface (S2) of the actuator are separated from each other, wherein the sensor further comprises: a substrate , and a light source part formed on the substrate , wherein the light source part is adapted to emit a detection light (LF) according to a reception state of a detection signal outputted from the actuator or according to a state of the sensor ; the door switch being characterised in that it further comprises: a light guide display part , comprising: a collector adapted to collect the detection light (LF); a diffuse light guide part formed to be connected to the collector and adapted to diffuse and emit the detection light (LF) collected by the collector ; and a back surface display part formed on the back surface (B1) side, which is a side opposite to the front surface (S1), of the sensor to be in contact with the diffuse light guide part and having a main surface adapted to emit the detection light (LF) emitted from the diffuse light guide part , wherein a cross-sectional area of the diffuse light guide part at the side in contact with or close to the back surface display part is larger than the cross-sectional area of the collector , wherein the diffuse light guide part is in a bilateral-symmetrical shape in a longitudinal direction of the main surface , which is parallel to the back surface (B1) of the sensor , wherein the back surface display part and the collector include surfaces parallel to the longitudinal direction, wherein the diffuse light guide part has a shape such that two parts thereof are extending separately in a predetermined angle with the collector as a reference point and the light guide part has a V-shape. a light guide display part , comprising: a collector adapted to collect the detection light (LF); a diffuse light guide part formed to be connected to the collector and adapted to diffuse and emit the detection light (LF) collected by the collector ; and a back surface display part formed on the back surface (B1) side, which is a side opposite to the front surface (S1), of the sensor to be in contact with the diffuse light guide part and having a main surface adapted to emit the detection light (LF) emitted from the diffuse light guide part , wherein a cross-sectional area of the diffuse light guide part at the side in contact with or close to the back surface display part is larger than the cross-sectional area of the collector , wherein the diffuse light guide part is in a bilateral-symmetrical shape in a longitudinal direction of the main surface , which is parallel to the back surface (B1) of the sensor , wherein the back surface display part and the collector include surfaces parallel to the longitudinal direction, wherein the diffuse light guide part has a shape such that two parts thereof are extending separately in a predetermined angle with the collector as a reference point and the light guide part has a V-shape. <EOS>