An endoscope apparatus is adapted to be inserted into an inside of a subject and observe the inside of the subject and includes: an observation optical system which has a first optical path and a second optical path with parallax an imaging portion on which a light passing through the first optical path and a light passing through the second optical path are formed a diaphragm portion which selectively blocks out the first optical path or the second optical path a distance measurement portion which measures a distance to the subject on the basis of parallax between a first image formed on the imaging portion via the first optical path and a second image formed on the imaging portion via the second optical path a displacement amount detection portion which detects a displacement amount between two first images acquired with a time interval therebetween and a measurement environment determination portion which determines, on the basis of the displacement amount, whether or not the first image and the second image are suitably used for measurement by the distance measurement portion.
