A young boy in Taiwan has been rescued after a freak accident left him dangling off his fifth-storey balcony for half-an-hour over the weekend.

The four-year-old had been left at home alone by his parents when he went to the balcony of his apartment in Pingtung City, south of the Taiwanese capital Taipei, and slipped through the security grille.

The toddler's entire body managed to fit through the grille, and he was only prevented from falling to his death by his head being caught between the bars.

Mobile footage recorded by one of the child’s neighbours shows the child attempting to hold his weight up with his arms.

After police and firefighters were called to help rescue the boy around 11.15am, men could be seen accessing the apartment's balcony from the floor above.

The boy was eventually freed after 30 minutes, when a rescuer abseiled down the outside of the building.

It is understood the child suffered minor injuries to his head and ears, including non-serious scrapes.

The boy's parents, who rushed to the hospital immediately after being told of the incident, could now face fines of up to NT$15,000 (AUD$665) for breaching Taiwanese child welfare laws, Newsweek reported.