In this endoscope apparatus, an imaging optical system is disposed in a distal end of an endoscope insertion unit. An measurement processing unit performs a measurement process by the principle of triangulation on the basis of an image corresponding to an optical image obtained via an imaging optical system and camera parameters of a first position and a second position. A reliability determination unit determines the reliability of the measurement process. The measurement process is based on a measurement point set in the image corresponding to the optical image obtained via the imaging optical system at the first position. A notification control unit sends a notification to prompt a user to perform an operation of moving the distal end in a direction from the second position toward the first position when the reliability determination unit determines that the reliability is low.