When an execution condition for a purge of supplying evaporated fuel gas to an intake pipe is met, a required purge ratio is set within a range equal to or higher than a lower-limit purge ratio, and a purge control valve is controlled using a driving duty based on the required purge ratio. In this case, when the execution condition is continuously met, an ejector pressure is estimated based on a pressure difference between a supercharging pressure and a pre-compressor pressure, and on the driving duty, and the lower-limit purge ratio is set based on a post-throttle-valve pressure and on the ejector pressure. The value of the lower-limit purge ratio is set to zero immediately after the execution condition switches from being not met to being met.