a probe which is inserted into a lumen of inside of a body , irradiates an observation object part of a physiological tissue with excitation light , and detects fluorescence resulting from the excitation light , wherein the probe including : a plus lens arranged facing toward a tip side of the probe ; and a plurality of optical fibers receiving the fluorescence at tip surfaces through the plus lens , wherein the tip surface are directed toward the plus lens and arranged in positions offset from an optical axis of the plus lens , wherein positions of the tip surface of at least optical fibers of which an amount of offset from the optical axis of the plus lens differ mutually among plurality of optical fibers are shifted mutually along the optical axis of the plus lens .