A hydraulic pressure control unit for a brake system mounted to a straddle-type vehicle and capable of executing anti-lock brake control, the hydraulic pressure control unit being configured to store a brake fluid that is released from a wheel cylinder during depressurization in the anti-lock brake control in an accumulator and to discharge the brake fluid in the accumulator to outside of the accumulator in a pumpless manner, the hydraulic pressure control unit comprising: a base body formed with: a master cylinder port to which a fluid pipe communicating with a master cylinder is connected; a wheel cylinder port to which a fluid pipe communicating with the wheel cylinder is connected; and an internal channel that communicates the master cylinder port and the wheel cylinder port with each other; an inlet valve and an outlet valve that are provided to the base body and open/close the internal channel during the anti-lock brake control; a first coil as a drive source of the inlet valve; a second coil as a drive source of the outlet valve; a circuit board that is electrically connected to the first coil and the second coil and controls energization of the first coil and the second coil; and a housing that is connected to the base body and accommodates the first coil, the second coil, and the circuit board, characterized in that: in the case where a perpendicular direction to a connection direction of the housing to the base body is set as a width direction, one of a paired side surfaces that oppose each other in the width direction in the housing is set as a first side surface, and the other thereof is set as a second side surface, a dimension in the width direction of the housing is greater than a dimension in the width direction of the base body, and in a state where the hydraulic pressure control unit is seen in the connection direction, a center in the width direction of the base body is located on the first side surface side from a center in the width direction of the housing. a base body formed with: a master cylinder port to which a fluid pipe communicating with a master cylinder is connected; a wheel cylinder port to which a fluid pipe communicating with the wheel cylinder is connected; and an internal channel that communicates the master cylinder port and the wheel cylinder port with each other; an inlet valve and an outlet valve that are provided to the base body and open/close the internal channel during the anti-lock brake control; a first coil as a drive source of the inlet valve; a second coil as a drive source of the outlet valve; a circuit board that is electrically connected to the first coil and the second coil and controls energization of the first coil and the second coil; and a housing that is connected to the base body and accommodates the first coil, the second coil, and the circuit board, characterized in that: in the case where a perpendicular direction to a connection direction of the housing to the base body is set as a width direction, one of a paired side surfaces that oppose each other in the width direction in the housing is set as a first side surface, and the other thereof is set as a second side surface, a dimension in the width direction of the housing is greater than a dimension in the width direction of the base body, and in a state where the hydraulic pressure control unit is seen in the connection direction, a center in the width direction of the base body is located on the first side surface side from a center in the width direction of the housing. in the case where a perpendicular direction to a connection direction of the housing to the base body is set as a width direction, one of a paired side surfaces that oppose each other in the width direction in the housing is set as a first side surface, and the other thereof is set as a second side surface, a dimension in the width direction of the housing is greater than a dimension in the width direction of the base body, and in a state where the hydraulic pressure control unit is seen in the connection direction, a center in the width direction of the base body is located on the first side surface side from a center in the width direction of the housing.