An extender lens is removably inserted into a master lens, performs an increase in a focal length without changing an imaging position due to insertion, and consists of a positive first lens group and a negative second lens group in order from the object side. The first lens group consists of one or more positive lenses in order from the object side, and a three-lens cemented lens having three lenses of a positive lens, a negative lens, and a positive lens having cemented together in order from the object side. The following Conditional Expression (1) relating to an Abbe number ν1n of the negative lens of the three-lens cemented lens is satisfied: 26