Abstract: A fuel supply control device including a purge control valve. The maximum purge rate, that is, the ratio between the amount of purge and the amount of intake air when the purge control valve is fully open, is stored in advance. The purge control valve is controlled in its duty ratio, which duty ratio is the target purge rate/maximum purge rate. When the purge is started, the target duty ratio is gradually increased. When the purge is performed and the feedback correction coefficient FAF falls, the feedback correction coefficient FAF is gradually returned to the FAF before the start of a purge, the purge A/F correction coefficient is increased, and the amount of injection is corrected by the sum of the purge A/F correction coefficient and the feedback correction coefficient.