An apparatus for estimating a shape of an insertion portion includes an insertion portion, an acceleration calculation unit calculating acceleration at measurement points, and a determination unit which determines whether the measurement points move. The apparatus further includes an attitude information calculation unit calculating attitude information of the measurement points in a resting state, an attitude estimation unit estimating a movement period attitude, a movement vector calculation unit calculating a movement vector of the measurement points, and a position calculation unit calculating a position of the measurement points. The apparatus further includes an image generation unit generating a display image expressing the position and the movement vector.
