PROBLEM TO BE SOLVED: To estimate a spinal column parameter indicating a state of a spinal column of an evaluation subject from data obtained by actually measuring a three-dimensional shape of a back face of the evaluation subject. A model holding unit holds a dorsal shape model that represents a three-dimensional shape of a human dorsal surface as a function of spinal column parameters. The back surface shape information input unit 12 receives input of measured shape data which is the measurement result of the three-dimensional shape of the back surface of the evaluation subject. The spinal column parameter estimation unit 18 aligns the back surface shape model and the measured shape data as necessary, and then changes the spinal column parameters so that the point groups of the back surface shape model and the actually measured shape data match. Transform the model. Then, the spinal column parameters at the time of coincidence are output as information indicating the state of the spinal column of the evaluation subject. [Selection diagram] Figure 1
