Provided is a method of producing pet food in which food granules of at least two colors are mixed together, including: a food granule producing process of producing food granules of at least two colors and a mixing process of mixing the food granules of at least two colors, in which the food granule producing process includes a powder raw ingredient mixing process of mixing together powder raw ingredients to obtain mixed powder, an extruding and granulating process of supplying the mixed powder to an extrusion granulator to continuously produce food granules, and a coloring process of performing coloring by adding an additive solution that contains a coloring component to the extrusion granulator, and the mixing process includes a process of sequentially putting the food granules of at least two colors into a tank to be layered and a process of discharging the food granules from the bottom of the tank to obtain a mixture of the food granules of at least two colors.