A probe device for optically measuring a condition of an object includes a light emitter for emitting a light to proceed into the object through a surface of the object, a light sensor for measuring an optical condition of the light proceeding from the surface through the object and subsequently emitted from the surface to reach the light sensor, and a body holding thereon at least one of the light emitter and the light sensor. The body includes at least one main protrusion protruding so as to face to the surface, and at least two sub-protrusions arranged around the at least one main protrusion and protruding so as to face to the surface.
