A driving tool including a timer assembly less susceptible to heat operates at a stable operating speed. The driving tool includes a trigger, a contact arm, and a timer assembly that operates in response to the trigger moving to a trigger-on-position with the contact arm remaining at an arm-off-position. The timer assembly includes a flywheel rotatable in response to the trigger moving to the trigger-on-position, and a contact restrictor movable between an unlock position at which the contact restrictor allows the contact arm to move to an arm-on-position and a lock position at which the contact restrictor restricts the contact arm from moving to the arm-on-position. The contact restrictor takes a predetermined period to move from the unlock position to the lock position in response to the trigger moving to the trigger-on-position. The predetermined period is defined by an inertial force generated by rotation of the flywheel.