A wavelength division element includes a first filter and a second filter.
The first filter has incident angle-to-transmission wavelength
characteristics and separates multiplexed lights in a plurality of
wavelength bands into first lights that are in a first wavelength band
and first reflected lights. The first filter allows the first lights to
pass through in a first direction and reflects the first reflected lights
in a second direction. The second filter is located in the second
direction and separates the first reflected lights into second lights
that are in a second wavelength band and second reflected lights. The
second filter allows the second lights to pass through in a third
direction and reflects the second reflected lights in a fourth direction.