Kalashnikov, who was in his 20s when he created the AK-47 just after World War II, died in his home city of Izhevsk, near the Ural Mountains, where his gun is still made, the agency cited a spokesman for the province’s president as saying.
The automatic rifle he designed became one of the world’s most familiar and widely used weapons.
Its comparative simplicity made it cheap to manufacture, as well as reliable and easy to maintain.
Although honoured by the state, Kalashnikov made little money from his gun. He once said he would have been better off designing a lawn mower.
Mikhail Kalashnikov was admitted to hospital with internal bleeding in November.
He was born on 10 November 1919 in western Siberia, one of 18 children.