A pet food with superior preference qualities for a pet, while including dietary fiber such as pulp. The pet food includes dietary fiber, in which the pet food contains lignin in an amount of no less than 0.5% by mass and no greater than 2.2% by mass. The pet food preferably contains the dietary fiber in an amount of no less than 10% by mass and no greater than 20% by mass. A fiber source material for pet food preferably includes lignin in an amount of no less than 5% by mass and no greater than 25% by mass. The pet food is preferably used as a cat food.