Abstract: A portable endoscope having a control part containing an entrance end portion of a light guide for transmitting light for illuminating an object, and an illuminating light supply unit containing a light source lamp for supplying illuminating light to the light guide. A connecting mechanism detachably connects the control part and the light supply unit. A switch for turning on/off the light source lamp is provided in the connecting mechanism. When the light supply unit is connected to the control part in a predetermined state, the switch is turned on; when the former is detached from the latter, the switch is turned off. An electric resistor may be provided for gradually reducing the electric resistance between the lamp and a power supply therefor from a high-resistance state to a low-resistance state as the switch is moved from an OFF position toward an ON position.