Abstract: The present invention is applied to endoscopes for the medical purpose to observe cavities in a body such as a stomach, a duodenum, a bronchus or the like and endoscopes for the industrial purpose to observe the interiors of a machine or component such as an engine. The endoscope according to the invention comprises: an insertable portion to be inserted into a portion to be observed in the cavity of body or the machine or component; a manual control portion connected to the proximal end of the insertable portion and having an ocular portion; and a connecting portion connected at one end thereof to the manual control portion and connected at the other end thereof to an external apparatus having a power source through a connector thereof. In the endoscope of this type, the connector can be removed from the external apparatus and water-tightly connected to the ocular portion.