Recently, legged robots that can move on various and complex environments have developed for tasks of rescue, exploration and so on in the dangerous space. Practical robots must be equipped with environmental cognition and motion transition system in addition to movement maneuver itself. Limb-type robots having redundancy and symmetry are able to work in the various environments. This paper describes movement of a Limb-type robot on a vertical ladder, which is a fundamental example of frame structures like a jungle gym or truss. We focus on environmental cognition by external sensors, motion transition from the floor to the ladder and maneuver for climbing the ladder. Simulation is conducted to design an analytical model of the robot and verify the proposed approach by using "Open Dynamics Engine".