Michael Payless, 33, was found dead in the southern Indiana town of Salem on Friday night.
Payless was watching television with two of his children when the other child, a 3-year-old boy, found the gun.
"The child accidentally discharged the loaded handgun ... Michael A. Payless was pronounced dead at the scene," an Indiana state police statement said.
Payless, with his wife, three children, and another juvenile, had been at the house doing some remodelling work, the statement said.
© Thomson Reuters 2012