A sample analysis system includes blood serum analysis units, blood plasma analysis units and urine analysis units which are arranged along a main conveyor line. The width size of each analysis unit on the side along the main conveyor line is the same. Each analysis unit can be removed integral with a sampling line and its rack transfer device from, the main conveyor line. Removed analysis units can be replaced by each other without changing the entry and exit positions for the sample rack. The conveyor line has the same number of line frame segments as the number of the analysis units.