The tourist parked his car outside a supermarket in Sant Joan d'Alacant and went in to do some shopping taking his three-year-old son with him but leaving the baby sleeping in the back of a car.
But the baby was spotted by concerned passersby who flagged down a Civil Guard patrol car at the beach resort in Alicante.
The officers smashed a window to reach the baby, were unable to rouse it and called an ambulance.
The 33-year-old father, who has not been named, returned from the supermarket to find police surrounding the car and his infant child about to be taken to hospital.
The man, who was reportedly on holiday at a nearby campsite with his wife and three children, was promptly arrested and now faces a charge of child negligence.
Authorities confirmed that the child was treated at the scene and fortunately showed no signs of ill health.