Judge William Sylvester said prosecutors have established probable cause to proceed with 166 felony counts, including murder and attempted murder.
A succession of police and federal agents testified that Holmes (25) spent weeks amassing guns and ammunition, concocted explosives to booby-trap his apartment and scouted the cinema.
Many legal analysts have said they expect the case to end with a plea bargain rather than a trial.
Tom Teves, whose son Alex was among the dead, said he would rather see Holmes plead guilty to first-degree murder, avoiding a traumatic trial, bringing a life sentence and closing the door to an insanity defence.
If found not guilty by reason of insanity, Holmes could conceivably be released some day .
"Don't pretend he's crazy," Mr Teves said. "He's not crazy. He's no more crazy than you and I."