An apparatus (100) for displaying a shape of an insertion portion includes a transformable insertion portion (210) and attitude acquisition units (110) which acquire acceleration applied to measurement points and attitude information of the measurement points. The apparatus (100) further includes a shape calculation unit (136), a movement determination unit (133), a movement period specification unit (134), an attitude estimation unit (143) and an image generation unit (146). The shape calculation unit (136) calculates attitudes and relative positions of the measurement points. The movement period specification unit (134) specifies a movement period based on the determination by the movement determination unit (133). The attitude estimation unit (143) estimates a movement period attitude. The movement vector calculation unit (144) calculates movement vectors of the measurement points during the movement period. The image generation unit (146) generates a display image expressing the relative positions and the movement vectors.
