A flow line specification unit selects, for each piece of mobile object identification information, position-score correspondence information that satisfies a criterion from among position-score correspondence information stored in state storage unit, as definite position-score correspondence information. The flow line specification unit repeatedly performs a process of reflecting the definite position-score correspondence information in position-score correspondence information of a time nearest a time corresponding to the definite position-score correspondence information and setting the position-score correspondence information of the nearest time as definite position-score correspondence information. And the flow line specification unit specifies a flow line of a mobile object from a score in position-score correspondence information of each time.