A knife includes a blade having a first side face and a second side face. The blade includes zirconia as a main component, and includes a cutting region including at least a ridge portion between the first side face and the second side face. When a portion including the cutting region in the first side face is referred to as a first cutting face, and a portion including the cutting region in the second side face is referred to as a second cutting face, the proportion of cubic crystals of zirconia in the first cutting face is larger than the proportion of cubic crystals of zirconia in the second cutting face.