To provide a fuel injection control device for a cylinder fuel injection type internal combustion engine setting an appropriate fuel injection period without relying on a fuel pressure sensor including a transient condition when fuel pressurization is stopped by control without causing large fluctuation of fuel pressure value used for fuel injection quantity control between the transition condition and the pressurization stop condition.

When pressurization by a high pressure fuel pump is stopped (expf=ON: Yes in S402), demand fuel injection quantity qinj is converted to fuel injection period tau based on established pressure of a pressure regulator (S404). Consequently, even if fuel pressure is lower than detection lower limit value, an appropriate fuel injection period tau can be calculated since the actual measurement fuel pressure by the fuel pressure sensor is not used even if the fuel pressure is made lower than a detection lower value. The appropriate fuel injection period tau can be calculated (s404) since conversion is done by using the estimated fuel pressure vpr calculated based on the fuel injection quantity and delivery fuel quantity of the high pressure fuel pump without using the actual measurement fuel pressure erp even during the transient period (Yes in s402). Consequently, the problem can be solved by that.