Lens apparatus and image pickup apparatus

An image pickup apparatus comprising a lens apparatus and an image pickup element for picking up an image formed by the lens apparatus,

• wherein the lens apparatus comprises:
• a main body configured to house an optical system;
• and
• a mount part detachably mountable to the main body and a camera apparatus,
• wherein the mount part includes a first electric contact part that contacts an electric contact part of the camera apparatus and a second electric contact part electrically conductive with the first electric contact part,
• wherein the main body comprises an electric substrate and a third electric contact part electrically conductive with the electric substrate,
• wherein the second electric contact part and the third electric contact part are in contact with each other by connecting the main body and the mount part to each other.