A sample processing system comprising: at least three sample processing units (4, 5); at least three sample transport units, respectively provided corresponding to the sample processing units (4, 5) and for respectively transporting a sample rack to the corresponding one of the sample processing units (4, 5); and a control section, wherein the sample transport units includes at least a first sample transport unit, a second sample transport unit adjacent to the first sample transport unit and a third sample transport unit adjacent to the second sample transport unit in order from the upstream in a transport direction, each of the sample transport units includes a transport path for transporting a sample rack to another sample transport unit on the downstream side and a transport member for moving a sample rack on the transport path, and for transporting a sample rack which is to be introduced to the first sample transport unit to a destination sample transport unit which is located downstream of the second sample transport unit, the control section is configured to perform the following process including: moving the transport members of the first and second sample transport units; characterized in that said process further includes: when the sample rack arrives at a predetermined position in the transport path of the first sample transport unit, determining whether or not the transport member of the third sample transport unit is in a standby state; and when the transport member of the third sample transport unit is in the standby state, moving the transport member of the third sample transport unit. at least three sample processing units (4, 5); at least three sample transport units, respectively provided corresponding to the sample processing units (4, 5) and for respectively transporting a sample rack to the corresponding one of the sample processing units (4, 5); and a control section, wherein the sample transport units includes at least a first sample transport unit, a second sample transport unit adjacent to the first sample transport unit and a third sample transport unit adjacent to the second sample transport unit in order from the upstream in a transport direction, each of the sample transport units includes a transport path for transporting a sample rack to another sample transport unit on the downstream side and a transport member for moving a sample rack on the transport path, and for transporting a sample rack which is to be introduced to the first sample transport unit to a destination sample transport unit which is located downstream of the second sample transport unit, the control section is configured to perform the following process including: moving the transport members of the first and second sample transport units; characterized in that said process further includes: when the sample rack arrives at a predetermined position in the transport path of the first sample transport unit, determining whether or not the transport member of the third sample transport unit is in a standby state; and when the transport member of the third sample transport unit is in the standby state, moving the transport member of the third sample transport unit. moving the transport members of the first and second sample transport units; characterized in that said process further includes: when the sample rack arrives at a predetermined position in the transport path of the first sample transport unit, determining whether or not the transport member of the third sample transport unit is in a standby state; and when the transport member of the third sample transport unit is in the standby state, moving the transport member of the third sample transport unit. when the sample rack arrives at a predetermined position in the transport path of the first sample transport unit, determining whether or not the transport member of the third sample transport unit is in a standby state; and when the transport member of the third sample transport unit is in the standby state, moving the transport member of the third sample transport unit.