A contact lens case including a cylindrical container body, a cap member for closing an opening of the container body, a support member which is attached at one end thereof to the cap member to extend therefrom in an axial direction of the container body, and a lens holder rotatably supported by the support member. The lens holder has one or more lens storage chamber each receiving the contact lens, and a plurality of holes which permit a liquid to flow therethrough. The present contact lens case further includes a detent structure for holding the lens holder selectively in a horizontal position in which the contact lens received in the holder has a horizontal attitude perpendicular to the axial direction of the container body, or in a vertical position in which the contact lens received has a vertical attitude parallel to the axial direction of the container body. Also disclosed is a lens treating device which uses the present contact lens case as an inner case that is axially slidden within an outer case for cleaning the contact lens stored therein.