Provided is a stroke simulator capable of suppressing occurrence of inclination of a piston with respect to a sliding surface formed in a cylinder. The stroke simulator includes a simulator piston which is displaced by sliding on a sliding surface formed in a first cylinder, and a first return spring which is housed in the first cylinder and applies, to the simulator piston, a reaction force which is generated by an elastic deformation of the spring under a pressing force due to a displacement of the simulator piston, and generates the reaction force which is applied to the simulator piston as a brake reaction force for a brake operating element. The stroke simulator is characterized in that a cup seal for sealing a gap formed between the sliding surface and the simulator piston is mounted in the middle in the axial direction of the sliding surface.