A vehicular hydraulic pressure generation device, comprising: a hydraulic pressure generation section having a master cylinder (34; 434) for generating a hydraulic pressure corresponding to an operation amount of a brake operation member by a driver; and a reaction force generation section (64; 164; 364) communicated with the hydraulic pressure generation section to generate a reaction force corresponding to the operation amount of the brake operation member, wherein the reaction force generation section (64; 164, 364) includes: a simulator piston that is operated to move in a forward direction or in a backward direction, corresponding to the hydraulic pressure generated by the hydraulic pressure generation section, the simulator piston being housed in a simulator housing to define a reaction-force hydraulic chamber; and an elastic portion provided on a side of the forward direction of the simulator piston, wherein the elastic portion is formed by a first elastic portion (68a; 368) having a first elastic modulus, a second elastic portion having a second elastic modulus larger than the first elastic modulus, and a third elastic portion (75; 175; 375) having a third elastic modulus smaller than the second elastic modulus, wherein the hydraulic pressure generation section includes: a first piston (40a; 440a) and a second piston (40b; 440b) provided to be forward and backward movable in the master cylinder (34; 434), in association with the brake operation member; a first hydraulic chamber (56a; 456a) partitioned by an inner wall portion of the master cylinder, the first piston, and the second piston; a second hydraulic chamber (56b; 456b) partitioned by the inner wall portion of the master cylinder and the second piston; a first spring member (50a; 450a) provided in the first hydraulic chamber (56a; 456a), the first spring member connecting the first piston and the second piston; and a second spring member (50b; 450b) provided in the second hydraulic chamber (56b; 456b), the second spring member connecting the second piston and the inner wall portion of the master cylinder, wherein the reaction-force hydraulic chamber of the reaction-force generation section receives the hydraulic pressure from the second hydraulic chamber (56b; 465b) to operate the simulator piston, characterized in that a maximum value of hydraulic pressure generated in the second hydraulic chamber (56b; 456b) is set smaller than a maximum value of hydraulic pressure generated in the first hydraulic chamber, and that the maximum capacity of the second hydraulic chamber (46b; 456b) of the master cylinder (34; 434) is set smaller than the maximum capacity of the reaction-force hydraulic chamber such that the simulator piston of the stroke simulator does not reach bottom of the simulator housing before the second piston (40b; 440b) reaches bottom of the master cylinder (43; 434). a hydraulic pressure generation section having a master cylinder (34; 434) for generating a hydraulic pressure corresponding to an operation amount of a brake operation member by a driver; and a reaction force generation section (64; 164; 364) communicated with the hydraulic pressure generation section to generate a reaction force corresponding to the operation amount of the brake operation member, a simulator piston that is operated to move in a forward direction or in a backward direction, corresponding to the hydraulic pressure generated by the hydraulic pressure generation section, the simulator piston being housed in a simulator housing to define a reaction-force hydraulic chamber; and an elastic portion provided on a side of the forward direction of the simulator piston, a first piston (40a; 440a) and a second piston (40b; 440b) provided to be forward and backward movable in the master cylinder (34; 434), in association with the brake operation member; a first hydraulic chamber (56a; 456a) partitioned by an inner wall portion of the master cylinder, the first piston, and the second piston; a second hydraulic chamber (56b; 456b) partitioned by the inner wall portion of the master cylinder and the second piston; a first spring member (50a; 450a) provided in the first hydraulic chamber (56a; 456a), the first spring member connecting the first piston and the second piston; and a second spring member (50b; 450b) provided in the second hydraulic chamber (56b; 456b), the second spring member connecting the second piston and the inner wall portion of the master cylinder,