A spray pump which sprays liquid contents, comprising: an under cap which has a through hole 111 at its center; an over cap which is engaged to the through hole 111 of the under cap 110 and has a stem installation hole at its inner side; a cylinder housing which is engaged to the bottom of the over cap and has a suction through hole at its lower side and a check valve installed at an inner, lower side of the top of the suction through hole for thereby allowing fluids to flow only in a suction direction; a stem which passes through the stem installation hole 121 of the over cap, the center of the stem being passed through from its top to bottom; a main spring 145 which is installed between the over cap and an outer circumferential surface of the stem; a piston rod which is inserted into the bottom of the stem and has, on its central axis, a fluid passage hole whose top is open and whose bottom is closed, at least two side passage holes 152 being formed at the lower side surface of the fluid passage hole; a first seal cap which is installed movable in upward and downward directions at the bottom of the piston rod 150 and closes the side passage hole at a descending point and opens the side passage hole at an ascending point, an outer circumferential surface of the first seal cap coming into close contact with an inner surface of the cylinder housing; a second seal cap which is engaged to the piston rod at the top of the first seal cap, an outer circumferential surface of the second seal cap coming into close contact with an inner surface of the cylinder housing; an inner spring which is installed between the second seal cap and the first seal cap; a first leakage discharge hole which is formed at a side surface wall of the cylinder housing and is positioned at the top of the Top Dead Point of the first seal cap and the bottom of the Bottom Dead Point; a second leakage discharge hole 136 which is formed at a side surface wall of the cylinder housing and is positioned at the bottom of the Top Dead Point of the second seal cap; a spray button which is engaged to the top of the stem and has a spray passage communicating in a lateral direction; and a spray nozzle member which is engaged to a discharge port of the spray passage. an under cap which has a through hole 111 at its center; an over cap which is engaged to the through hole 111 of the under cap 110 and has a stem installation hole at its inner side; a cylinder housing which is engaged to the bottom of the over cap and has a suction through hole at its lower side and a check valve installed at an inner, lower side of the top of the suction through hole for thereby allowing fluids to flow only in a suction direction; a stem which passes through the stem installation hole 121 of the over cap, the center of the stem being passed through from its top to bottom; a main spring 145 which is installed between the over cap and an outer circumferential surface of the stem; a piston rod which is inserted into the bottom of the stem and has, on its central axis, a fluid passage hole whose top is open and whose bottom is closed, at least two side passage holes 152 being formed at the lower side surface of the fluid passage hole; a first seal cap which is installed movable in upward and downward directions at the bottom of the piston rod 150 and closes the side passage hole at a descending point and opens the side passage hole at an ascending point, an outer circumferential surface of the first seal cap coming into close contact with an inner surface of the cylinder housing; a second seal cap which is engaged to the piston rod at the top of the first seal cap, an outer circumferential surface of the second seal cap coming into close contact with an inner surface of the cylinder housing; an inner spring which is installed between the second seal cap and the first seal cap; a first leakage discharge hole which is formed at a side surface wall of the cylinder housing and is positioned at the top of the Top Dead Point of the first seal cap and the bottom of the Bottom Dead Point; a second leakage discharge hole 136 which is formed at a side surface wall of the cylinder housing and is positioned at the bottom of the Top Dead Point of the second seal cap; a spray button which is engaged to the top of the stem and has a spray passage communicating in a lateral direction; and a spray nozzle member which is engaged to a discharge port of the spray passage.