A fuel injection controller for an internal combustion engine that is applied to an accumulator type fuel injection system including a common rail for accumulating and holding high-pressure fuel, a fuel pump for pressure-feeding a fuel to the common rail, and a plurality of fuel injectors that are disposed in each cylinder of a multi-cylinder internal combustion engine and are adapted to sequentially inject the high-pressure fuel accumulated in the common rail in a predetermined order, the fuel injection controller comprising: injection cylinder pressure detecting means (20a, 30) adapted to sequentially detect a fuel pressure varied when the fuel injector injects the fuel in an injection cylinder; non-injection cylinder pressure detecting means (20a, 30) adapted to sequentially detect a fuel pressure varied when the fuel pump pressure-feeds the fuel in a non-injection cylinder that is not the injection cylinder, wherein the non-injection cylinder pressure detecting means (20a, 30) includes: means for computing a fuel not-pressure-feeding pressure that is a fuel pressure when the fuel pump does not pressure-feed the fuel; means for computing a fuel pressure-feeding pressure that is a fuel pressure when the fuel pump pressure-feeds the fuel; and means for computing a quantity of pressure variation (ΔP) caused when the fuel pump pressure-feeds the fuel by a difference between the fuel not-pressure-feeding pressure and the fuel pressure-feeding pressure; injection pressure computing means adapted to correct a detection value of the injection cylinder pressure detecting means by a detection value of the non-injection cylinder pressure detecting means when the fuel injector injects the fuel, thereby computing an injection pressure; the injection pressure computing means adapted to correct the detection value of the injection cylinder pressure detecting means by the quantity of pressure variation (ΔP) to compute the injection pressure; and injection characteristic computing means adapted to compute an injection characteristic by the fuel injector on the basis of the injection pressure computed by the injection pressure computing means. injection cylinder pressure detecting means (20a, 30) adapted to sequentially detect a fuel pressure varied when the fuel injector injects the fuel in an injection cylinder; non-injection cylinder pressure detecting means (20a, 30) adapted to sequentially detect a fuel pressure varied when the fuel pump pressure-feeds the fuel in a non-injection cylinder that is not the injection cylinder, wherein the non-injection cylinder pressure detecting means (20a, 30) includes: means for computing a fuel not-pressure-feeding pressure that is a fuel pressure when the fuel pump does not pressure-feed the fuel; means for computing a fuel pressure-feeding pressure that is a fuel pressure when the fuel pump pressure-feeds the fuel; and means for computing a quantity of pressure variation (ΔP) caused when the fuel pump pressure-feeds the fuel by a difference between the fuel not-pressure-feeding pressure and the fuel pressure-feeding pressure; means for computing a fuel not-pressure-feeding pressure that is a fuel pressure when the fuel pump does not pressure-feed the fuel; means for computing a fuel pressure-feeding pressure that is a fuel pressure when the fuel pump pressure-feeds the fuel; and means for computing a quantity of pressure variation (ΔP) caused when the fuel pump pressure-feeds the fuel by a difference between the fuel not-pressure-feeding pressure and the fuel pressure-feeding pressure; injection pressure computing means adapted to correct a detection value of the injection cylinder pressure detecting means by a detection value of the non-injection cylinder pressure detecting means when the fuel injector injects the fuel, thereby computing an injection pressure; the injection pressure computing means adapted to correct the detection value of the injection cylinder pressure detecting means by the quantity of pressure variation (ΔP) to compute the injection pressure; and injection characteristic computing means adapted to compute an injection characteristic by the fuel injector on the basis of the injection pressure computed by the injection pressure computing means.