Lens unit and optical unit

Provided are a lens unit and an optical unit having high airtightness and having high lens fixing strength. The lens unit (100) has multiple lenses (1-4) arranged along the optical axis (L) of the lens unit, and a tubular holder (7) that holds these lenses (1-4). A convex lens surface (1a) is formed on the lens (1), and the lens surface (1a) protrudes from a large-diameter part (74) provided at the foremost end of the holder (7), and is secured by crimping. A continuous coating is applied to the lens surface (1a) and the surface of a crimping part (76) around the periphery of the lens surface. The process for coating the lens surface (1a) is performed with the lens (1) secured by crimping in the holder (7), so the gap between the lens surface (1a) and the crimping part (76) is sealed by the coating material, thereby improving airtightness.