According to an embodiment, a lens device includes a filter, an entire area of which transmits light of a common color. The filter includes a first filter region and a second filter region. The first filter region transmits light that is a first combination of colors out of colors of light to be received by an image sensor. The second filter region transmits light that is a second combination of colors of the colors of the light to be received by the image sensor. The first and second combinations of colors each include the common color.