Police did not say what the arrests were for at Monday night's game, when the 49ers clinched a playoff spot after beating the Atlanta Falcons 34-24. The San Francisco Chronicle reported that at least some of the people were arrested on suspicion of stealing seats from the stadium.
In addition to the arrests, police said 81 people were ejected and seven people were cited.
Police Chief Greg Suhr had said earlier that fans could expect 50 percent more officers at Monday's game than a regular night game.
The Niners began playing at The Stick in 1971. The team is moving to a new, $1.2 billion stadium next season.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.