The elderly man wandered into the sex shop in Place Belfort in Toulouse on Sunday afternoon.
According to a report on the local website La Depeche, he perused the rows of sex toys before entering a private cabin to watch a pornographic movie.
But at some point during the film his heart gave in and he collapsed to the floor.
Another of the shop's customers raised the alarm and paramedics were called to the scene at around 3.20pm.
An ambulance was despatched and a first aid team attempted to resuscitate the man but it was in vain and the octogenarian was pronounced dead at the scene.
An autopsy was due to take place to find the cause of death.