An automatic analyzer, comprising: a reaction disk for mounting thereon a plurality of reaction containers; a reagent disk for setting a reagent container storing a reagent; a reagent dispensation mechanism for dispensing the reagent stored in the reagent container to the reaction containers; a sample container transport mechanism for transporting a sample container storing a sample; a sample dispensation mechanism for dispensing the sample stored in the sample container to the reaction containers; and a control unit for controlling the reaction disk, the reagent disk, the reagent dispensation mechanism, the sample container transport mechanism, and the sample dispensation mechanism, wherein the reagent dispensation mechanism is adapted to dispense a detergent to the reaction containers, and the automatic analyzer comprises a storage unit for storing, on a daily basis, information on the reaction containers to be cleaned in such a manner that all the reaction containers mounted on the reaction disk are to be cleaned within a plurality of days, characterized in that the control unit is adapted to control the sample dispensation mechanism, the reaction disk, and the reagent dispensation mechanism in such a manner that during an operation state after the sample to be analyzed has been dispensed to one of the reaction containers, the sample to be analyzed is analyzed, the detergent rather than a sample is dispensed to one of the reaction containers to be cleaned of an appointed day, in accordance with the information on the reaction containers to be cleaned of the appointed day stored in the storage unit, and the one of the reaction containers to be cleaned is soaked and washed for a certain period of time, and the control unit is adapted to control the sample dispensation mechanism, the reaction disk, and the reagent dispensation mechanism in such a manner that the samples to be analyzed are dispensed to the reaction containers at a sample dispensation position of the sample dispensation mechanism always at an interval between dispensations of the detergent to the reaction containers to be cleaned of the appointed day, in accordance with the information on the reaction containers to be cleaned of the appointed day stored in the storage unit. a reaction disk for mounting thereon a plurality of reaction containers; a reagent disk for setting a reagent container storing a reagent; a reagent dispensation mechanism for dispensing the reagent stored in the reagent container to the reaction containers; a sample container transport mechanism for transporting a sample container storing a sample; a sample dispensation mechanism for dispensing the sample stored in the sample container to the reaction containers; and a control unit for controlling the reaction disk, the reagent disk, the reagent dispensation mechanism, the sample container transport mechanism, and the sample dispensation mechanism, wherein the reagent dispensation mechanism is adapted to dispense a detergent to the reaction containers, and the automatic analyzer comprises a storage unit for storing, on a daily basis, information on the reaction containers to be cleaned in such a manner that all the reaction containers mounted on the reaction disk are to be cleaned within a plurality of days, characterized in that the control unit is adapted to control the sample dispensation mechanism, the reaction disk, and the reagent dispensation mechanism in such a manner that during an operation state after the sample to be analyzed has been dispensed to one of the reaction containers, the sample to be analyzed is analyzed, the detergent rather than a sample is dispensed to one of the reaction containers to be cleaned of an appointed day, in accordance with the information on the reaction containers to be cleaned of the appointed day stored in the storage unit, and the one of the reaction containers to be cleaned is soaked and washed for a certain period of time, and the control unit is adapted to control the sample dispensation mechanism, the reaction disk, and the reagent dispensation mechanism in such a manner that the samples to be analyzed are dispensed to the reaction containers at a sample dispensation position of the sample dispensation mechanism always at an interval between dispensations of the detergent to the reaction containers to be cleaned of the appointed day, in accordance with the information on the reaction containers to be cleaned of the appointed day stored in the storage unit.