A sample processing apparatus comprising: a plurality of sample processing units, each configured to process a sample contained in a sample container; a transport apparatus that is configured to transport a sample rack holding a sample container to at least any one of the plurality of sample processing units; a rack feeding section that is configured to receive a sample rack and feeds the received sample rack to a transport line of the transport apparatus; and a controller capable of instructing the transport apparatus to transport a sample rack fed by the rack feeding section to (a) a sample processing unit which can accept a subsequent sample rack more rapidly than any other sample processing unit or (b) a sample processing unit having a lower processing load than any other sample processing unit; the sample processing apparatus further comprising a rack set section on which a sample rack is set by a user and which is configured to transfer the set sample rack to the rack feeding section, characterised in that when a reception interval at which the rack feeding section receives sample racks is not greater than a predetermined interval, the controller is configured to instruct the transport apparatus to transport the sample rack fed by the rack feeding section to (a) the sample processing unit which can accept the subsequent sample rack more rapidly than any other sample processing unit, and when the reception interval is greater than the predetermined interval, the controller is configured to instruct the transport apparatus to transport the sample rack fed by the rack feeding section to (b) the sample processing unit having the lower processing load than any other sample processing unit. a plurality of sample processing units, each configured to process a sample contained in a sample container; a transport apparatus that is configured to transport a sample rack holding a sample container to at least any one of the plurality of sample processing units; a rack feeding section that is configured to receive a sample rack and feeds the received sample rack to a transport line of the transport apparatus; and a controller capable of instructing the transport apparatus to transport a sample rack fed by the rack feeding section to (a) a sample processing unit which can accept a subsequent sample rack more rapidly than any other sample processing unit or (b) a sample processing unit having a lower processing load than any other sample processing unit; the sample processing apparatus further comprising a rack set section on which a sample rack is set by a user and which is configured to transfer the set sample rack to the rack feeding section, characterised in that when a reception interval at which the rack feeding section receives sample racks is not greater than a predetermined interval, the controller is configured to instruct the transport apparatus to transport the sample rack fed by the rack feeding section to (a) the sample processing unit which can accept the subsequent sample rack more rapidly than any other sample processing unit, and when the reception interval is greater than the predetermined interval, the controller is configured to instruct the transport apparatus to transport the sample rack fed by the rack feeding section to (b) the sample processing unit having the lower processing load than any other sample processing unit.