An automatic analyzer including a sample container transportation mechanism that places and transports a sample container containing a sample to be analyzed, a reagent container holding mechanism (12a, 12b) that places and holds a reagent container (19a, 19b) containing a reagent for reacting with the sample, a reaction mechanism that places a reaction container for reacting the sample with the reagent, a sample dispensing mechanism that dispenses the sample in the sample container as a specimen in the reaction container, a reagent dispensing mechanism (10a, 10b) that dispenses the reagent in the reagent container (19a, 19b) into the reaction container, and a measuring device (14, 15) that measures a reaction solution in which the sample dispensed as the specimen in the reaction container and the reagent are mixed together, the automatic analyzer comprising: a control device that controls the operation of the automatic analyzer; a first storage device that stores sample information including the measurement result of the reaction solution for each sample; and a second storage device that stores the sample information on at least some of the samples among the sample information stored in the first storage device, wherein when the automatic analyzer reaches a predetermined operation state, the control device performs a backup process of backing up the sample information on the samples satisfying a predetermined backup condition from the first storage device to the second storage device, characterised in that the backup process includes deleting the sample information on the backed-up samples from the first storage device, the information to be deleted and backed up is narrowed down to the sample information on the samples satisfying the predetermined backup condition, and the backup condition includes at least one of that the sample information on the sample has already been transmitted to another system provided outside the automatic analyzer, that the sample information on the sample has been completed for all of predetermined items, and there is no abnormality in all of the items, and that the sample information on the sample has been completed for all of predetermined items, and there is an abnormality in the items. a control device that controls the operation of the automatic analyzer; a first storage device that stores sample information including the measurement result of the reaction solution for each sample; and a second storage device that stores the sample information on at least some of the samples among the sample information stored in the first storage device, wherein when the automatic analyzer reaches a predetermined operation state, the control device performs a backup process of backing up the sample information on the samples satisfying a predetermined backup condition from the first storage device to the second storage device, characterised in that the backup process includes deleting the sample information on the backed-up samples from the first storage device, the information to be deleted and backed up is narrowed down to the sample information on the samples satisfying the predetermined backup condition, and the backup condition includes at least one of that the sample information on the sample has already been transmitted to another system provided outside the automatic analyzer, that the sample information on the sample has been completed for all of predetermined items, and there is no abnormality in all of the items, and that the sample information on the sample has been completed for all of predetermined items, and there is an abnormality in the items.