An automatic sample introduction device includes a needle, a sample loop, a mixer and a suction injection switch mechanism. The mixer is provided between the needle and the sample loop. The suction injection switch mechanism sequentially sucks first and second fluids into the sample loop through the needle and the mixer and injects the first and second fluids held in the sample loop into a predetermined injection port. A chromatograph includes the automatic sample introduction device having the above-mentioned configuration, an analysis column and a detector. The analysis column is connected to the injection port of the automatic sample introduction device, and the detector is connected to the analysis column.