To provide an evaporating fuel purging control device for an internal combustion engine, improving purging controllability, air-fuel ratio controllability and drivability by correcting the variation of the characteristics of a flow rate due to a change in operating condition such as intake pressure.

A deviation between a target flow ratio corresponding to target driving duty depending on the characteristics of a purge valve and an actual flow ratio is estimated from intake pressure and the target flow ratio, and the target driving duty corresponding to the deviation is calculated (S110-S130). Thus, a purge flow rate corresponding to the target driving duty and the flow rate linearity of the duty are obtained. The duty is set so that the purge flow rate is greater on a low duty side as the intake pressure is higher. In the case of the purge valve constructed to be closed with negative pressure, the purge flow rate corresponding to the driving duty is obtained on the low duty side in an operating condition with higher intake pressure. As the intake pressure is lower, the characteristics of the flow rate moves closer to a line of an inclination of 1, securing the flow rate linearity of the duty.