A first lens group having a negative power and having at least a negative lens having a concave surface facing the image side, a positive meniscus lens having a concave surface facing the object side, a meniscus lens having a convex surface facing the object side, a negative lens and a positive lens A third lens group having at least a positive lens having a convex surface facing the object side, a second lens group having a positive power having at least a cemented lens to which the endoscope is attached, The condition is satisfied.像側に凹面を向けた負レンズ、物体側に凹面を向けた正メニスカスレンズを少なくとも有する負のパワーを持つ第一のレンズ群、物体側に凸面を向けたメニスカスレンズ、負レンズと正レンズとを接合した接合レンズを少なくとも有する正のパワーを持つ第二のレンズ群、物体側に凸面を向けた正レンズを少なくとも有する第三のレンズ群からなるからなる内視鏡用変倍光学系を所定の条件を満たすように構成する。
