An acceleration/deceleration detecting system includes an acceleration/deceleration detector configured to be disposed in a measurement object and detect acceleration/deceleration of the measurement object, an acceleration/deceleration device configured to accelerate or decelerate the measurement object, and a calculation device configured to determine that a detection value of the acceleration/deceleration detector is an offset error or a detection error of the acceleration/deceleration detector, when an actual acceleration/deceleration direction of the measurement object is different from an acceleration/deceleration direction shown by a detection value of the acceleration/deceleration detector in a state that the measurement object is accelerated or decelerated by the acceleration/deceleration device.