Provided is an automatic stop and restart device for an engine that is capable of suppressing occurrence of an abnormal condition even if a transmission state is changed during an engine restart process after an engine restart condition is satisfied in an automatic engine stop process. A controller performs the automatic engine stop process and the engine restart process. If a determined state of a transmission is a drive range, a transmission state determination unit drives a pinion gear thrust unit at timing determined by a first pinion gear thrust timing determination unit. If the determined state of the transmission is a non-drive range, the transmission state determination unit drives the pinion gear thrust unit at timing determined by a second pinion gear thrust timing determination unit.