A valve timing adjusting device including a first rotor, a lock pin for locking a relative rotation between the first rotor and a second rotor at the most advanced position, and operating by fluid control pressure to release the lock, wherein rotor start-up delaying means is provided for operating the lock pin by the fluid control pressure in the lock releasing direction, and then rotating the second rotor in the lagged direction when the second rotor starts rotating from the most advanced position to the lagged direction.