Eye-watering video footage shows a construction worker plunging almost 20 feet through a factory roof — and painfully landing crotch-first on the metal handle of a machine.

James Cranswick, 26, smashed through a skylight and squirmed in agony in the harrowing clip released Wednesday by Britain’s Health and Safety Executive (HSE) watchdog — which said he was “lucky to be alive.”

Cranswick was hauling materials from one side of the roof to the other while erecting scaffolding when he accidentally stepped onto the light, described as “almost invisible” to workers.

He hit the truck and was seen clutching his crotch following the accident that happened in the West Yorkshire, England, warehouse in January last year.

Cranswick broke an arm and a leg and suffered head injuries — and HSE inspector Shauna Halstead said he is “lucky to be alive.”