A railcar collision energy absorbing device includes: an energy absorbing element crushed in collision; and a casing extending in a car longitudinal direction so as to accommodate the energy absorbing element. One end of the casing is supported by a main structure of a railcar. The casing is constituted by a plurality of tubular bodies whose overlapping portions are coupled to each other. The casing telescopically contracts in the collision by breaking of a coupling portion between the tubular bodies.