Police say the man was on his way to work and the axe was one of his tools.
People who had spotted him carrying the implement called the 911 emergency line around 9 a.m., prompting the police intervention.
Officers intercepted the man at the east-end Berri-UQAM subway station.
Montreal Transit Commission regulations forbid the unsecured transportation of anything that can be considered a weapon.
Such items as axes can only be transported in a container.
Montreal police say they are happy people are being vigilant even if the incident turned out to be a false alarm.