A device for detecting opening/closing of a charger lid provided in the vicinity of a battery charging opening for a vehicle body, the device comprising: an illumination means provided in the battery charging opening and capable of illuminating an inside of the battery charging opening; characterized by a first urging means for urging the charger lid in a closing direction; a push rod provided in the battery charging opening and capable of pushing up the charger lid; a switch means for turning on/off the illumination means; a second urging means for urging the charger lid in an opening direction; and a push-push mechanism (63, 75, 76, 68, 79, 80), wherein when the charger lid is located at a closed position for closing the battery charging opening, the push-push mechanism (63, 75, 76, 68, 79, 80) holds the push rod in a standby state when the charger lid located at the closed position is pressed and the standby state of the push rod is cancelled, the push-push mechanism (63, 75, 76, 68, 79, 80) opens the charger lid by pushing up the push rod by an urging force of the second urging means, when the switch means is turned off by the push rod in the standby state, the illumination means is turned off, when the switch means is turned on by the push rod no longer in the standby state, the illumination means is turned on, characterized in that, a display means for displaying charging-related information is provided at the battery charging opening, the charging-related information is a charging state of an onboard secondary battery, and the display means is a charging indicator indicating the charging state, the device being characterized in that: the switch means and the charging indicator are integrated by a common insulator, and the insulator includes a connection terminal (40, 41, 49) to be connected to a circuit of each of the switch means and the charging indicator. an illumination means provided in the battery charging opening and capable of illuminating an inside of the battery charging opening; characterized by a first urging means for urging the charger lid in a closing direction; a push rod provided in the battery charging opening and capable of pushing up the charger lid; a switch means for turning on/off the illumination means; a second urging means for urging the charger lid in an opening direction; and a push-push mechanism (63, 75, 76, 68, 79, 80), wherein when the charger lid is located at a closed position for closing the battery charging opening, the push-push mechanism (63, 75, 76, 68, 79, 80) holds the push rod in a standby state when the charger lid located at the closed position is pressed and the standby state of the push rod is cancelled, the push-push mechanism (63, 75, 76, 68, 79, 80) opens the charger lid by pushing up the push rod by an urging force of the second urging means, when the switch means is turned off by the push rod in the standby state, the illumination means is turned off, when the switch means is turned on by the push rod no longer in the standby state, the illumination means is turned on, characterized in that, a display means for displaying charging-related information is provided at the battery charging opening, the charging-related information is a charging state of an onboard secondary battery, and the display means is a charging indicator indicating the charging state, the device being characterized in that: the switch means and the charging indicator are integrated by a common insulator, and the insulator includes a connection terminal (40, 41, 49) to be connected to a circuit of each of the switch means and the charging indicator. the switch means and the charging indicator are integrated by a common insulator, and the insulator includes a connection terminal (40, 41, 49) to be connected to a circuit of each of the switch means and the charging indicator.