To continue animal individual control including a plurality of individuals even having the plurality of the individuals in which individual identification information is not directly obtained.

A weight acquisition part 101 acquires weight information and an individual ID reading part 102 acquires an individual ID. When acquisition of individual ID fails, a marking part 103 has a marking 202 on a pig 200 in a pattern different in each individual and a storage treatment part 109 stores weight information in association with a pattern ID of the marking 202 in a memory part 106. On the contrary, when acquisition of individual ID succeeds, the storage treatment part 109 stores weight information in association with the individual ID in the memory part 106. An estimation part 107 estimates which individual in which the pig 200 has the marking 202 is and associates the individual ID with the pattern ID. The estimation is based on weight information associated with the individual ID for a plurality of individuals in the past and weight information associated with the pattern ID.