Garban, who was still a member of the board, said in his letter of resignation that "these past months have been some of the most painful of my life."
He became the first member of the board of trustees to step down in the wake of the accusations involving Sandusky and the eventual trial in which the former assistant football coach was convicted of 45 counts of sexual abuse against 10 boys in a 15-year period.
"The horrific allegations that came to light in November have haunted us all, but nothing we have experienced compares to that of Jerry Sandusky's victims," Garban said in his letter. "My thoughts and prayers will remain with them always."
Garban became a member of the board of trustees in 1998. He was chairman in 2010 and 2011.
Karen Peetz, the board's current chairwoman, announced she had accepted Garban's resignation.
"I want to sincerely thank him for his many years of service to Penn State University and for the leadership he exhibited today," Peetz said.