An object is to provide a control board, an inverter device, and an integrated-inverter electric compressor that are capable of improving electromagnetic compatibility (EMC property) and improving reliability against input/output of electromagnetic noise, which shows a tendency towards greater complexity and intensity. A control board to which two power systems, that is, a low-voltage power system and a high-voltage power system, are inputs, comprising a low-voltage circuit and a high-voltage circuit, and a low-voltage-side ground region and a high-voltage-side ground region that are formed in correspondence with the circuits, respectively, wherein frame ground regions are provided at a plurality of positions on the control board, and a plurality of communication line patterns connected to the low-voltage circuit are respectively connected to both the low-voltage-side ground region and the frame ground region through capacitance elements with various capacitances.