A passenger protection apparatus includes a detector, an adjuster, a controller, and a setting unit. The detector is configured to detect an environmental condition outside a vehicle; the adjuster is configured to be able to correct a sitting posture of a passenger to sit on a seat in a proper position; the controller is configured to control actuation of the adjuster; and the setting unit is configured to set a time frame divided into a plurality of frames until a predicted collision between an own vehicle and an object outside the vehicle, based on a result of detection by the detector. The controller controls the actuation of the adjuster to correct the sitting posture of the passenger in a correction frame at least contained in the time frame.