An acquisition unit acquires the width-direction acceleration and the vertical-direction acceleration of a surface of a structure on which a moving object moves from an acceleration sensor provided in the structure on which the moving object moves. A displacement computation unit computes the vertical-direction displacement of the structure on the basis of the vertical-direction acceleration. A correlation determination unit determines the correlation between the width-direction acceleration and the vertical-direction displacement. A movement detection unit detects the movement of the moving object on the structure on the basis of the correlation.