The optical scanning endoscope apparatus (10) includes: an illumination optical fiber (11) guiding light form lasers (33R, 33G, 33B) and irradiating the light toward an object (100) from an oscillatably-supported tip part of the fiber; an actuator (21) vibratorily driving the tip part of the illumination optical fiber (11); a photodetector (35) detecting light resulting from the object (100) irradiated with the light from the lasers (33R, 33G, 33B) and converting the detected light into an electric signal; a signal processor (37) generating pixel information based on the electric signal output by the photodetector (35); and a light detection controller (31a) controlling a detection property of the photodetector (35) in a period other than an effective detection period.