A fluid pressure pump comprising: a port plate having a first port and a second port, one of which can function as a suction port and the other of which can function as a discharge port; and a piston unit, wherein said port plate and said piston unit are arranged to rotate relatively around a rotation axis, wherein said piston unit comprises: a barrel having a plurality of cylinders; a plurality of pistons configured to carry out a reciprocating motion in said plurality of cylinders, respectively; and a valve plate having a plurality of valve plate holes formed to be respectively connected with said plurality of cylinders, wherein said plurality of valve plate holes are arranged on a circumference around the rotation axis, and each of said first port and said second port is formed to have an arc shape around the rotation axis, wherein said port plate comprises: a plurality of first bridges configured to divide said first port in a circumferential direction to provide a plurality of first port holes; and a plurality of second bridges configured to divide said second port in the circumferential direction to provide a plurality of second port holes, characterized in that the arrangement is such that, when a first area is defined as an overlapped area between said plurality of first bridges and one of said valve plate holes which changes based on the relative rotation of said piston unit and said port plate around the rotation axis in a view parallel to the rotation axis, and when a second area is defined as an overlapped area between said plurality of second bridges and another one of said valve plate holes which changes based on the relative rotation, a quotient of a maximum value of the first area divided by the area of said one valve plate hole and a quotient of a maximum value of the second area divided by the area of said other valve plate hole are both smaller than 0.65. a port plate having a first port and a second port, one of which can function as a suction port and the other of which can function as a discharge port; and a piston unit, wherein said port plate and said piston unit are arranged to rotate relatively around a rotation axis, wherein said piston unit comprises: a barrel having a plurality of cylinders; a plurality of pistons configured to carry out a reciprocating motion in said plurality of cylinders, respectively; and a valve plate having a plurality of valve plate holes formed to be respectively connected with said plurality of cylinders, a barrel having a plurality of cylinders; a plurality of pistons configured to carry out a reciprocating motion in said plurality of cylinders, respectively; and a valve plate having a plurality of valve plate holes formed to be respectively connected with said plurality of cylinders, wherein said plurality of valve plate holes are arranged on a circumference around the rotation axis, and each of said first port and said second port is formed to have an arc shape around the rotation axis, wherein said port plate comprises: a plurality of first bridges configured to divide said first port in a circumferential direction to provide a plurality of first port holes; and a plurality of second bridges configured to divide said second port in the circumferential direction to provide a plurality of second port holes, characterized in that the arrangement is such that, when a first area is defined as an overlapped area between said plurality of first bridges and one of said valve plate holes which changes based on the relative rotation of said piston unit and said port plate around the rotation axis in a view parallel to the rotation axis, and when a second area is defined as an overlapped area between said plurality of second bridges and another one of said valve plate holes which changes based on the relative rotation, a quotient of a maximum value of the first area divided by the area of said one valve plate hole and a quotient of a maximum value of the second area divided by the area of said other valve plate hole are both smaller than 0.65. a plurality of first bridges configured to divide said first port in a circumferential direction to provide a plurality of first port holes; and a plurality of second bridges configured to divide said second port in the circumferential direction to provide a plurality of second port holes, characterized in that the arrangement is such that, when a first area is defined as an overlapped area between said plurality of first bridges and one of said valve plate holes which changes based on the relative rotation of said piston unit and said port plate around the rotation axis in a view parallel to the rotation axis, and when a second area is defined as an overlapped area between said plurality of second bridges and another one of said valve plate holes which changes based on the relative rotation, a quotient of a maximum value of the first area divided by the area of said one valve plate hole and a quotient of a maximum value of the second area divided by the area of said other valve plate hole are both smaller than 0.65.