An endoscope apparatus comprising: an endoscope including at least an elongated insertion section having flexibility and an image pickup device, the insertion section including, at a distal end portion, an observation window configured to form an observation optical system and an illumination window configured to form an illumination optical system and the image pickup device including an image pickup surface on which an optical image passing through the observation window is formed; an apparatus body - having a flat rectangular parallelepiped shape comprising a front principal plane which is one of surfaces having a largest area, a right side surface section and a left side surface section and a rear surface opposing the principal plane, and - incorporating, on the front principal plane, a display section configured to display an image picked up by the image pickup device; wherein the endoscope further comprises an operation section coupled to a proximal end portion of the insertion section, wherein the operation section, which is configured to function as a holding member configured to hold the insertion section in a wound state, is attached to the rear surface, and wherein the endoscope apparatus further comprises an attaching and detaching mechanism section (9, 30) which i) enables the operation section to be detachably attached to the rear surface and which ii) comprises a body attaching and detaching section provided on the rear surface and a hanger provided on the operation section, the operation section being attached to the rear surface by the attaching and detaching mechanism section (9, 30). an endoscope including at least an elongated insertion section having flexibility and an image pickup device, the insertion section including, at a distal end portion, an observation window configured to form an observation optical system and an illumination window configured to form an illumination optical system and the image pickup device including an image pickup surface on which an optical image passing through the observation window is formed; an apparatus body - having a flat rectangular parallelepiped shape comprising a front principal plane which is one of surfaces having a largest area, a right side surface section and a left side surface section and a rear surface opposing the principal plane, and - incorporating, on the front principal plane, a display section configured to display an image picked up by the image pickup device; wherein the endoscope further comprises - having a flat rectangular parallelepiped shape comprising a front principal plane which is one of surfaces having a largest area, a right side surface section and a left side surface section and a rear surface opposing the principal plane, and - incorporating, on the front principal plane, a display section configured to display an image picked up by the image pickup device; wherein the endoscope further comprises an operation section coupled to a proximal end portion of the insertion section, wherein the operation section, which is configured to function as a holding member configured to hold the insertion section in a wound state, is attached to the rear surface, and wherein the endoscope apparatus further comprises an attaching and detaching mechanism section (9, 30) which i) enables the operation section to be detachably attached to the rear surface and which ii) comprises a body attaching and detaching section provided on the rear surface and a hanger provided on the operation section, the operation section being attached to the rear surface by the attaching and detaching mechanism section (9, 30).