To minimize the consumption of a reagent in an FIA method or an r-FIA method.

This reagent and sample injecting device is provided with a reagent feeding means provided with a liquid feed pump 11 for transporting the reagent and a valve means V11 installed in a primary side of the pump 11 and switching feeding of the reagent and carrier gas, a sample feeding means provided with a liquid feed pump 12b for transporting a sample and a syringe 12a injecting the sample fed from the pump 12b into the reagent fed from the reagent feeding means, and a control means 10 controlling the reagent feeding means and the sample feeding means. The control means 10 controls so that the syringe 12a injects the sample in the reagent after a certain time from a start of the valve means V11 for feeding the carrier gas.