A differential-pressure flow meter having a pair of pressure-sensing devices (12A, 12B) fixed to a base member on upstream and downstream sides of an orifice member to determine a flow rate based on a pressure difference measured by the pressure-sensing devices (12A, 12B) between the two sides of the orifice member along a flow channel formed in respective housings (19A, 19B) of the first and second pressure sensing devices, between which the orifice member is removably installed, the first pressure-sensing device having a first sensor amplifier that amplifies the fluid pressure measured by a first pressure-sensing element and the second pressure-sensing device having a second sensor amplifier that amplifies the fluid pressure measured by a second pressure-sensing element, the differential-pressure flow meter comprising: a power circuit to which an external wiring is connected and that is supplied with power from an exterior through the external wiring; a pressure difference-sensing part that determines the pressure differences between the fluid pressure amplified by the first sensor amplifier and the fluid pressure amplified by the second sensor amplifier; and a flow rate converting part that determines the flow rate of the fluid flowing on the basis of the difference determined by the pressure-difference sensing part, wherein the power circuit, the pressure-difference sensing part, and the flow rate converting part, are included in a main control board disposed in a board installation space formed inside the base member, and the first sensor amplifier and the second sensor amplifier are respectively constituted by a first specific control board and a second specific control board, disposed near the respective pressure-sensing elements (15A, 15B) installed in the respective pressure-sensing devices (12A, 12B), and wherein the main control board, the first specific control board and the second specific control board are electrically connected by wires passing through a plurality of wiring conduits provided in housings (19A, 19B) of the first pressure-sensing device and the second pressure-sensing device. a power circuit to which an external wiring is connected and that is supplied with power from an exterior through the external wiring; a pressure difference-sensing part that determines the pressure differences between the fluid pressure amplified by the first sensor amplifier and the fluid pressure amplified by the second sensor amplifier; and a flow rate converting part that determines the flow rate of the fluid flowing on the basis of the difference determined by the pressure-difference sensing part, wherein the power circuit, the pressure-difference sensing part, and the flow rate converting part, are included in a main control board disposed in a board installation space formed inside the base member, and the first sensor amplifier and the second sensor amplifier are respectively constituted by a first specific control board and a second specific control board, disposed near the respective pressure-sensing elements (15A, 15B) installed in the respective pressure-sensing devices (12A, 12B), and wherein the main control board, the first specific control board and the second specific control board are electrically connected by wires passing through a plurality of wiring conduits provided in housings (19A, 19B) of the first pressure-sensing device and the second pressure-sensing device.