Manson did not attend the hearing, which began at 8:30 a.m. at Corcoran State Prison. He has not attended a parole hearing since 1997.
"At his age, I think he doesn't care," said Deputy District Attorney Patrick Sequeira. "He would be lost if he got out. He's completely institutionalized."
The parole board commissioner said Manson accumulated more than 100 serious disciplinary violations while in prison, that he's shown no indication of remorse for his nine murder convictions, and that he hasn't participated in any self-help programs - or shown any parole plans.
"The prisoner is not suitable for parole because the inmate would pose an unreasonable risk of dangers if released from prison," said California Board of Parole Hearings Commissioner John Peck.
Manson was convicted in the 1969 killings of pregnant actress Sharon Tate and four others. He was originally sentenced to death, but his sentenced was modified to life in prison when the California Supreme Court briefly outlawed the death penalty in 1972.
Playing heavily into the board's decision to deny parole was something Manson said recently to one of his prison psychiatrists that Peck read aloud during the hearing.
"'I am special. I am not like the average inmate. I have put five people in the grave. I've been in prison most of my life. I am a very dangerous man.' And this panel agrees with that statement," Peck said.
The commissioner described Manson's crimes as especially heinous, atrocious and cruel, with a callous disregard for human suffering.
Manson has a steady stream of visitors who submit requests to see him, including college students writing papers about him, said Theresa Cisneros, spokeswoman for Corcoran State Prison. Cisneros added that Manson receives more mail than most prisoners.
The Associated Press contributed to this report.