A hydraulic pressure generation apparatus , including: a base body ; a motor attached to the base body ; a master cylinder which generates a brake hydraulic pressure by a first piston which is linked to a brake manipulator (P); and a slave cylinder which generates a brake hydraulic pressure by a second piston which has the motor as a drive source, wherein the base body includes: a first cylinder hole having a closed bottom in which the first piston is inserted; and a second cylinder hole having a closed bottom in which the second piston is inserted, characterized in that the first cylinder hole and the second cylinder hole have respective openings in a respective surface of the base body located on one side thereof, an axial line (L1) of the first cylinder hole , an axial line (L2) of the second cylinder hole , and an axial line (L4) of an output shaft of the motor are arranged approximately parallel with each other, and when the base body is viewed from said one side of the base body , and the surfaces in which the first cylinder hole and the second cylinder hole have the respective openings are oriented vertically, the output shaft of the motor is located on one side of a vertical reference plane (S2) which includes the axial line (L1) of the first cylinder hole , the second cylinder hole is located on the other side of the vertical reference plane (S2), and the axial line (L1) of the first cylinder hole , the axial line (L2) of the second cylinder hole and the axial line (L4) of the output shaft of the motor have such a positional relationship that lines connecting them form a triangle, with the first cylinder hole being located at the top apex of the triangle and the second cylinder hole and the output shaft being located at the ends of the base of the triangle in the horizontal left-right direction. a base body ; a motor attached to the base body ; a master cylinder which generates a brake hydraulic pressure by a first piston which is linked to a brake manipulator (P); and a slave cylinder which generates a brake hydraulic pressure by a second piston which has the motor as a drive source, wherein the base body includes: a first cylinder hole having a closed bottom in which the first piston is inserted; and a second cylinder hole having a closed bottom in which the second piston is inserted, a first cylinder hole having a closed bottom in which the first piston is inserted; and a second cylinder hole having a closed bottom in which the second piston is inserted, characterized in that the first cylinder hole and the second cylinder hole have respective openings in a respective surface of the base body located on one side thereof, an axial line (L1) of the first cylinder hole , an axial line (L2) of the second cylinder hole , and an axial line (L4) of an output shaft of the motor are arranged approximately parallel with each other, and when the base body is viewed from said one side of the base body , and the surfaces in which the first cylinder hole and the second cylinder hole have the respective openings are oriented vertically, the output shaft of the motor is located on one side of a vertical reference plane (S2) which includes the axial line (L1) of the first cylinder hole , the second cylinder hole is located on the other side of the vertical reference plane (S2), and the axial line (L1) of the first cylinder hole , the axial line (L2) of the second cylinder hole and the axial line (L4) of the output shaft of the motor have such a positional relationship that lines connecting them form a triangle, with the first cylinder hole being located at the top apex of the triangle and the second cylinder hole and the output shaft being located at the ends of the base of the triangle in the horizontal left-right direction. <EOS>