1. An endoscope apparatus comprising: a heart rate sensor configured to contact a subject's skin and detect a movement of an organ of the subject and the sensor configured to output a detection signal of the organ; an endoscope configured for insertion into the subject, the scope comprising an image sensor configured to capture a plurality of images of the organ; and a processor comprising hardware, the processor operably connected to the heart rate sensor and the image sensor, the processor configured to: receive a plurality of images, each of the plurality of images captured by the image sensor of the organ; calculate a first movement evaluation value for at least some of the plurality of images; and determine a still image from the plurality of images based on the first movement evaluation value and the detection signal of the organ.