An endoscope apparatus configured to measure a subject using a pattern projection image of the subject on which a light and dark pattern of light is projected, the endoscope apparatus comprising: an insertion section having a tip portion with a tip surface; a light-transmissive cover member provided at the tip surface; an imaging section provided at the tip portion and configured to acquire the image of the subject through the cover member; an illumination section configured to emit illumination light that illuminates an observation visual field of the imaging section; a pattern projection section configured to project the light and dark pattern onto the subject; an objective optical system provided at the tip portion and configured to form the image of the subject on the imaging section; one or more illumination windows provided at the tip surface and through which the illumination light can be emitted; and a projection window provided at the tip surface and through which the light and dark pattern can be projected onto the subject from the pattern projection section; wherein the pattern projection section comprises a projecting light source configured to emit light, and a pattern generator configured to generate the light and dark pattern and arranged on an optical path for the light emitted from the projecting light source; wherein the light and dark pattern is a pattern with an intensity distribution in which a bright portion and a dark portion are alternately arranged, the objective optical system is arranged so that an optical axis on an emission side that is directed to the imaging section from the objective optical system among optical axes of the objective optical system is parallel to and eccentric from a central axis of the insertion section, the objective optical system is a side-view-type objective optical system of which the cover member is exposed to the tip surface and has an optical axis on an incidence side arranged at a twisted position with respect to the central axis of the insertion section, a line obtained by projecting the central axis of the insertion section perpendicularly to the tip surface is defined as a virtual centerline, the cover member is arranged at a position where the center thereof does not intersect the virtual centerline, the illumination window is arranged on the virtual centerline, and the projection window is arranged at a position where the center thereof does not intersect the virtual centerline. an insertion section having a tip portion with a tip surface; a light-transmissive cover member provided at the tip surface; an imaging section provided at the tip portion and configured to acquire the image of the subject through the cover member; an illumination section configured to emit illumination light that illuminates an observation visual field of the imaging section; a pattern projection section configured to project the light and dark pattern onto the subject; an objective optical system provided at the tip portion and configured to form the image of the subject on the imaging section; one or more illumination windows provided at the tip surface and through which the illumination light can be emitted; and a projection window provided at the tip surface and through which the light and dark pattern can be projected onto the subject from the pattern projection section; wherein the pattern projection section comprises a projecting light source configured to emit light, and a pattern generator configured to generate the light and dark pattern and arranged on an optical path for the light emitted from the projecting light source; wherein