To provide a lateral steady acceleration simulation system for railway vehicle, which is capable of simulating a situation in which lateral steady acceleration is applied to a railway vehicle for a long period of time, while having a compact structure. In a riding quality simulation system of the invention, a control unit activates each of actuators (40), thereby making a simulated passenger room (10) roll. Then, the simulated passenger room (10) is gradually inclined, while a component force, along an inclined plane, of gravitational acceleration g, that is, a first reproductive acceleration G1 is generated depending on an angle of inclination θ. In this manner, a person riding on the simulated passenger room (10) bodily senses the first reproductive acceleration G1 by the roll. At the same time, the control unit moves the simulated passenger room 10, by means of a laterally moving device, in either of the left or right direction with acceleration G. In this manner, the person riding on the simulated passenger room (10) bodily senses a second reproductive acceleration G2. As a result, the person riding on the simulated passenger room (10) bodily senses a combination of the first and second reproductive accelerations G1 and G2 as lateral steady acceleration on a railway.