Provided is an optical device including an object-side body portion to and from which an eyepiece-side support member supporting an eyepiece system optical component can be attached and removed; an objective system optical component supported on the object-side body portion; a housing section that houses at least a portion of the eyepiece-side support member; a manipulation member by which a rotation manipulation is performed on the housing section; a following member that is driven and displaced by the manipulation member being rotated; and a gripping member that has at least a portion thereof arranged inside the housing section and grips the eyepiece-side support member when the following member is displaced. The manipulation member rotates freely relative to the following member when a gripping force exerted on the eyepiece-side support member by the gripping member reaches a prescribed value.