California Highway Patrol Sgt. Kurt Stormes says the man tossed money from his car on Interstate 210 in the Los Angeles suburb of Glendora shortly before noon Sunday.
Stormes says about 10 people ran into traffic lanes to get it.
CHP officers recovered about $1,000.
The 56-year-old man then went to the Police Department in nearby Azusa. Police Lt. Steve Hunt says the man told officers he wanted to kill himself and was hospitalized for mental evaluation. His name wasn't released.
Authorities asked anyone who picked up the man's money to turn it in so it can be returned.