The present invention relates to an apparatus and a method of manufacturing metal nanoparticles, and more particularly to an apparatus including: a precursor supplying part which supplies a precursor solution of metal nanoparticles; a first heating part which is connected with the precursor supplying part, includes a reactor channel having a diameter of 1 to 50 mm, and is heated to the temperature range where any particle is not produced; a second heating part which is connected with the first heating part, includes a reactor channel having a diameter of 1 to 50 mm, and is heated to the temperature range where particles are produced; and a cooler which is connected with the second heating part and collects and cools metal nanoparticles produced at the second heating part which allows continuous mass production of metal nanoparticles.