There is provided a lens adapter easily detachable to and from a case, with an optical component such as a filter, a conversion lens etc. attached without a dedicated member on a camera side for attaching. The lens adapter has an attachment section attached to the case of the camera, and a lens barrel housing section provided at the attachment section for housing a lens barrel. The attachment section has first and second members swingably engaging in a detachable manner and is attached to the case in a state that the first and second members sandwich the case in a direction from front to rear of the case. A metallic ring is embedded on a front end of a cylindrical wall section forming a lens barrel housing section. A female screw for attaching an optical component such as a filter, a conversion lens etc. is formed on an inner peripheral surface of the ring.