Scott MacLeod told CBC's Daybreak he was boarding the metro when the doors slammed shut on him and another passenger.
"I wasn't running down the stairs, plowing into a group of people to get in the car. I was just a bystander, getting on as per usual," he said.
Once the doors shut, MacLeod said he squeezed through to get inside the car, while the other person stepped backwards off the train.
From inside the car, MacLeod said he saw two metro security officers approach the subway train and flag the conductor to stop.
They signalled MacLeod to get off the train and handed him the ticket. MacLeod said he tried to explain the situation, but the officers insisted that he had forced the doors open.
"I apologized, I said this was not my intention," MacLeod said.
"I really believe there was not adequate time for myself and the other fellow to get on the train."
MacLeod said the fine is excessive and plans to contest it and take it to court if necessary.
STM spokeswoman Amélie Regis said riders often hold open doors or pull emergency brakes unnecessarily, resulting in about half of the delays on the trains.
"The metro stops an average 80 times a year because someone has held the door," she said.
MacLeod said the officers told him they would be monitoring the metro on a regular basis because they have a problem with people stopping the trains.