Abstract: A parking brake system for a vehicle comprising a brake pedal vertically penetrating a floor of a vehicle, a first engaging member integrally provided on the brake pedal below the floor, a parking brake operating member disposed above the floor, a second engaging member for engaging with the catch pivoted on a chassis of the vehicle below the floor so as to be shifted between a locking position and an unlocking position in accordance with operation of the parking brake operating member, and an overcenter spring interposed between the second engaging member and the chassis so as to alternately bias the second engaging member toward the locking position and the unlocking position. The parking brake operating member is shifted so as to be retained at either a releasing position or a parking position. The second engaging member is retained at the locking position when the parking brake lever is located at the parking position, and if the brake pedal is lowered, engages with the first engaging member.