Mitchell Garcia, 58, of San Mateo, was identified as the lone suspect involved in two bank robberies.
During the first robbery in April, Garcia allegedly displayed the butt of a gun from the front waistband of his pants, police said.
In a separate robbery on July 5, Garcia allegedly displayed what he claimed to be an explosive device, police said.
Detectives obtained a $200,000 warrant for Garcia's arrest, according to police.
Garcia was arrested at a residential hotel in San Francisco's Mission Terrace neighborhood, police said.