To provide a fuel injection device for an internal combustion engine, which prevents defects caused by deposits accumulated on a clearance portion in the injector.

An ECU reads in data Tf from a fuel temperature sensor detecting fuel temperature in a common rail (S2), performs a processing of calculating a fuel temperature weighting coefficient k from a weighting map (S3) and calculates a fuel temperature integration value (S4). The fuel temperature integration value is obtained from Tf=kTf+Tf. When the fuel temperature integration value Tf is larger than a predetermined value w (S5:YES), it is determined that a deposit amount reaches a specified one and a warning lamp is lighted (S6).