A fuel supply device for an internal combustion engine, comprising: a low-pressure fuel pump for sucking fuel from a fuel tank; a high-pressure fuel pump for pressurizing the fuel discharged from the low-pressure fuel pump; an accumulator for accumulating the fuel pressurized by the high-pressure fuel pump; fuel injection valves for directly injecting the fuel accumulated in the accumulator into cylinders of an internal combustion engine; a relief valve for restricting an upper limit value of a fuel pressure in the accumulator; a high-pressure fuel pressure sensor for detecting the fuel pressure in the accumulator; and a control unit programmed to: set a target fuel injection pressure corresponding to an engine operating state, control the high-pressure fuel pump based on a detection value of the high-pressure fuel pressure sensor and the target fuel injection pressure so that the fuel pressure in the accumulator reaches the target fuel injection pressure, set a fuel injection pulse width of the fuel injection valves based on the detection value of the high-pressure fuel pressure sensor, and determine the presence of an abnormality of the high-pressure fuel pressure sensor, characterized in that the control unit is further programmed to, when the presence of the abnormality of the high-pressure fuel pressure sensor is determined: set the high-pressure fuel pump in an operational state with a maximum discharge amount or set the high-pressure fuel pump in a non-operational state, when the presence of the abnormality of the high-pressure fuel pressure sensor is determined, correct the detection value of the high-pressure fuel pressure sensor to be a value equal to the target fuel injection pressure, and set the fuel injection pulse width of the fuel injection valves based on the corrected detection value of the high-pressure fuel pressure sensor. a low-pressure fuel pump for sucking fuel from a fuel tank; a high-pressure fuel pump for pressurizing the fuel discharged from the low-pressure fuel pump; an accumulator for accumulating the fuel pressurized by the high-pressure fuel pump; fuel injection valves for directly injecting the fuel accumulated in the accumulator into cylinders of an internal combustion engine; a relief valve for restricting an upper limit value of a fuel pressure in the accumulator; a high-pressure fuel pressure sensor for detecting the fuel pressure in the accumulator; and a control unit programmed to: set a target fuel injection pressure corresponding to an engine operating state, control the high-pressure fuel pump based on a detection value of the high-pressure fuel pressure sensor and the target fuel injection pressure so that the fuel pressure in the accumulator reaches the target fuel injection pressure, set a fuel injection pulse width of the fuel injection valves based on the detection value of the high-pressure fuel pressure sensor, and determine the presence of an abnormality of the high-pressure fuel pressure sensor, set a target fuel injection pressure corresponding to an engine operating state, control the high-pressure fuel pump based on a detection value of the high-pressure fuel pressure sensor and the target fuel injection pressure so that the fuel pressure in the accumulator reaches the target fuel injection pressure, set a fuel injection pulse width of the fuel injection valves based on the detection value of the high-pressure fuel pressure sensor, and determine the presence of an abnormality of the high-pressure fuel pressure sensor, characterized in that the control unit is further programmed to, when the presence of the abnormality of the high-pressure fuel pressure sensor is determined: set the high-pressure fuel pump in an operational state with a maximum discharge amount or set the high-pressure fuel pump in a non-operational state, when the presence of the abnormality of the high-pressure fuel pressure sensor is determined, correct the detection value of the high-pressure fuel pressure sensor to be a value equal to the target fuel injection pressure, and set the fuel injection pulse width of the fuel injection valves based on the corrected detection value of the high-pressure fuel pressure sensor. set the high-pressure fuel pump in an operational state with a maximum discharge amount or set the high-pressure fuel pump in a non-operational state, when the presence of the abnormality of the high-pressure fuel pressure sensor is determined, correct the detection value of the high-pressure fuel pressure sensor to be a value equal to the target fuel injection pressure, and set the fuel injection pulse width of the fuel injection valves based on the corrected detection value of the high-pressure fuel pressure sensor.