The Russian has dominated the tour so far.
The reigning tour champion had won four of five races before Friday's mass start and set off in a superior overall lead in Val di Fiemme.
He stayed in the lead throughout the race, but was really challenged at the end.
Behind came both the Italian Francesco De Fabiani and compatriot Alexei Chervotkin, but Bolshunov was once again the strongest in the race and won 1.8 seconds ahead of De Fabiani and 3.7 ahead of Chervotkin.
Best Swede was Oskar Svensson in 15th place, before Björn Sandström in 19th.
William Poromaa was good with halfway into the race when he and the Russian Yevgeny Belov fell and Poromaa broke the pole.
Calle Halfvarsson broke the race.