The image capturing device according to the present invention is configured so that only the lens barrel having the entrance window and the refractive optical system can be expanded and contracted. Therefore, the structure can be simplified. In addition, the entrance window is located at the in-use position where the entrance window protrudes from the image capturing device body when the lens barrel is expanded, and is located at the not-in-use position where the entrance window is housed in the image capturing device body when the lens barrel is contracted. Therefore, the size of the camera can be reduced. Furthermore, when the image capturing device is not in use, the entrance window is housed in the image capturing device body. Therefore, any barrier is not needed, and the structure can be simplified.