The present invention provides a light selective transmission filter which selectively shields light and has a high transmittance of light at a specific wavelength such as visible rays, and which has a sufficiently reduced thickness and excellent heat resistance. The present invention further provides a lens unit including such a light selective transmission filter. The light selective transmission filter selectively reducing a transmittance of light has a thickness of less than 200 μm and includes a base material containing a functional film with reflow resistance. The lens unit includes such a light selective transmission filter and a lens.