A device for restarting an engine capable of suppressing unnecessary restart of an engine is provided. After a predetermined period (T) has elapsed since a time of setting a restart condition including a detection result indicating a dead state of a transmission (step S3), restarting of the engine is stopped (step S6) when engine rotation speed is not greater than a predetermined value Nth (step S4) or the engine restart is continued when the engine rotation speed is greater than the predetermined value Nth (step S4).