A host system recognizes a sample pretreatment system at which a primary sample has first arrived and records the information, if multiple containers containing the primary sample are input. Upon issuing an analysis request to the sample pretreatment system, the host system determines whether the primary sample (sample bearing the same barcode for sample identification) is input to a system different from the system to which the sample was input for the first time and, if that is the case, then determines that “the sample is input to the wrong system” and issues a “do-nothing request” (request to do nothing) so that an aliquoting operation will not be performed. Given the “do-nothing request” from the host system, the sample pretreatment system does not prepare any aliquot sample and places the input sample onto a tray in a predetermined position.
