In a parking brake system, a locking tooth (17a) of a ratchet plate (17) is configured to have: a first area (S1) in which a locking claw (19c) of a ratchet pawl (19) comes into contact with the locking tooth and remains there in an equilibrium state when a parking brake lever is pulled up and thereafter loosened while a release rod being pressed; and a second area (S2) in which the locking claw remains there in a state of halfway engagement of tooth tips when a pressing force of the release rod is released. With this configuration, when the locking claw (19c) comes into contact with a portion closer to a tip of the locking tooth (17a) beyond the first area (S1), a line of force (F1) is maintained due to the pressing force of the release rod. Accordingly, the locking claw (19c) does not become in the state of halfway engagement of tooth tips at the second area (S2), and the locking claw (19c) slides towered the tooth tip to prevent beforehand the occurrence of the state of halfway engagement of tooth tips. Further, even if an occupant erroneously pulls up the parking brake lever toward an operational position while the release rod being pressed, it is possible to reliably prevent the occurrence of the state of halfway engagement of tooth tips in a ratchet mechanism.