An endoscope apparatus having a function of switching between the 2-D observation for a planar view and the 3-D observation for a stereoscopic view, includes an image Processor which carries out processing of reducing a distortion of an image pickup optical system for an image pickup signal achieved by an image pickup element of the endoscope apparatus at the time of the 3-D observation, and the image Processor carries out image processing that satisfies the following conditional expression (1): 0.1