An insertion device includes: a linear member inserted into an insertion portion to be movable a plurality of mobile bodies provided in a state of being strung together on an outer periphery of the linear member and being movable with respect to the linear member a restricting member fixed with respect to the linear member, the restricting member restricting a movable range of each mobile body with respect to the linear member and preventing each of the mobile bodies from falling off and a fixing pin being movable between a first position and a second position at which the fixing pin is fitted in between any adjacent two mobile bodies.
