A robber was caught on camera forcing a 54-year-old man to lie down in a Bronx apartment at gunpoint — stealing nearly $40,000 in jewelry, including a diamond-studded Rolex, according to cops.

Footage from just before 3:30 p.m. Tuesday shows the victim first forced to raise his hands as a robber pulls a handgun from his camouflage jacket and points it straight at him.

As the attacker appears to cock the weapon, the victim removes his own fur-lined parka-style coat and slowly crawls face-forward on the floor near two rows of cinema-style seats.

The crook stole a $10,000, 14-karat Cuban link gold chain and a diamond Rolex watch worth a hefty $27,000, police said.

The surveillance footage caught him also pulling out a cellphone, and police say a second crook joined him, stealing the victim’s cellphone, car keys and around $300 in cash.

The duo fled the building near East 165 Street and Cauldwell Avenue in a black Mercedes sedan, police said.

The victim, who was not injured, may have previously met one of the attackers and allowed him into the building, a police source said.