The present invention relates to an inverter booster pump system capable of determining leaking of suction and discharge headers, an upper casing, a check valve, and a mechanical seal of a pump, flooding of a machine room, and the like. The inverter booster pump system according to the present invention is characterized in that a pump (30) is installed on each support plate (20) of a bed (10); a first groove (21) and a second groove (22) are formed in the shape of a straight line on each support plate (20); the second groove (22) is placed right under a discharge side check valve (40); the top of a guide pipe (50) is connected to an upper casing (31) and the bottom of the guide pipe (50) is placed in the first groove (21); a first contact point sensor (25) is installed in the first groove (21); a second contact point sensor (26) is installed in the second groove (22); and signals from the first and second contact point sensors (25, 26) are provided to a control unit to enable the control unit to determine whether leaking or flooding occurs.