Provided is an optical scanning device. The optical scanning device includes a swingable reflection unit; a blocking unit that is provided in the reflection unit to move in linkage with the reflection unit; and a sensor unit that includes an output unit configured to output a detection target and a detection unit configured to detect the detection target, wherein, when the reflection unit is in a predetermined swing angle range, the blocking unit blocks a path of the detection target between the output unit and the detection unit.