It is intended to provide an endurance test apparatus whereby the behaviors of a vessel caused by a biomechanical burden can be simulated using a relatively simple constitution so that the endurance of a medical instrument (for example, a stent or an artificial vessel after anastomosis) can be tested in a similar state to an actual vessel, and an endurance test method therefor. Namely, an endurance test apparatus (10) comprises a simulated vessel (31) made of an elastic body, first and second holding members (32, 33) respectively supporting the both ends in the axial direction of the simulated vessel (31) and making the both ends relatively rotatable and interval-adjustable, and first and second motors (14, 15) operating these holding members (32, 33). The simulated vessel (31) is supported by the first and second holding members (32, 33) in a state stretched from its inherent length under a tensile force. Due to the driving motors (14, 15), the holding members (32, 33) elongate and contract the simulated vessel (31), which is in the stretched state as described above, while twisting it.