110 operation 506 in this case the third stored good related data m 3 corresponds to information of the goods stored in the first to third storage cells 204 a to 204 c for this reason the first and second stored good related data m 1 and m 2 are removed from the third stored good related data m 3 to extract information of the goods stored only in the third storage cell 204 c and then the third stored good related data m 3 containing no first and second stored good related data m 1 and m 2 is stored in the memory unit 110 m 3 m 3 u2212 m 2 m 1 here m 2 is second stored good related data containing no first stored good related data m 1 finally another search is performed using the fourth antenna 206 d to collect fourth stored good related data m 4 and the collected fourth stored good related data m 4 is stored in the memory unit 110 operation 508 in this case the fourth stored good related data m 4 corresponds to information of the goods stored in the first to fourth storage cells 204 a to 204 d for this reason the first to third stored good related data m 1 to m 3 are removed from the fourth stored good related data m 4 to extract information of the goods stored only in the fourth storage cell 204 d and then the fourth stored good related data m 4 containing no first to third stored good related data m 1 to m 3 is stored in the memory unit 110 m 4 m 4 u2212 m 3 m 2 m 1 here m 3 is third stored good related data containing no first and second.