A sample injection part connected to a column to inject a sample into the column; a sample injection needle attachable to the sample injection part; a sample suction part connectable to the sample injection needle and configured to cause a predetermined amount of the sample to be drawn by suction into the sample injection needle upon connecting to the sample connection needle; a mobile phase supply part configured to supply the column with a mobile phase; a first switching valve for selectively connecting the sample injection needle to one of the sample suction part and the mobile phase supply part; and a second switching valve, including the sample injection part, for supplying the sample and the mobile phase to the column via the sample injection needle in the case of having the sample injection needle attached to the sample injection part and for supplying the mobile phase to the column via the first switching valve in the case of having the sample injection needle removed from the sample injection part are included.