A technique for simplifying the structure of an idling stop device. The idling stop device 100 includes a deceleration detector 200 which detects decelerations of a vehicle. The idling stop device 100 also includes an estimation part 350 which acquires, based on the deceleration detected by the deceleration detector 200, first deceleration when a vehicle is decelerated to a preset speed of less. Based on the acquired first deceleration, the estimation part 350 estimates a first brake pressure applied to the vehicle when the vehicle is decelerated to the preset speed or less.