Abstract: A tire-pressure control apparatus includes an air pump AP capable of supplying compressed air to a tire air chamber Rb, a mechanical control valve device VA which permits and prohibits supply of compressed air from the air pump AP to the tire air chamber Rb, a valve-state detection sensor (stroke sensor S1) for detecting the state of the control valve device VA, and an electric control apparatus ECU. The electric control apparatus ECU includes time measurement for measuring a pressure increasing time which is a time period starting when the supply of compressed air from the air pump AP to the tire air chamber Rb is started and ending when the supply of compressed air is stopped, and a pressure decreasing time which is a time period starting when the supply of compressed air is stopped and ending when the supply of compressed air is started (resumed).