To generate the signal of a mask for the easier capturing of an observed object within a screen.

The side view type electronic endoscope is constituted of an insertion tube inserted into the body cavity, an objective optical system disposed at the side part in the longitudinal direction of the insertion tube, an imaging means which receives the light flux formed by the objective optical system to be converted to the image signal and a mask signal generation means which generates the signal of the mask for making the angle of the visual field in the longitudinal direction wider than that in the direction orthogonal to the longitudinal direction.