Oil pump rotor

To provide an oil pump rotor capable of achieving improvement in quietness and volume efficiency. When the diameter of a base circle bi of an inner rotor is bi, the diameter of a first external rolling circle Di is Di, the diameter of a first internal rolling circle di is di, the diameter of a base circle bo of an outer rotor is bo, the diameter of a second external rolling circle Do is Do, the diameter of a second internal rolling circle do is do, and an eccentric amount between the inner rotor and the outer rotor is e, the oil pump rotor satisfies the following relations: bi=n*( Di+ di), bo=(n+1)*( Do+ do) and Di+ di=2e, or Do+ do=2e and Do > Di, di > do. Furthermore, when a clearance between the inner rotor and the outer rotor is t and the relation of Di+ di=2e is established, the oil pump rotor satisfies the relation: 0.3 ≤ (( Do+ do)-( Di+ di))*(n+1)/t ≤ 0.6, or when the relation of Do+ ]do=2e is established, the oil pump rotor satisfies the relation: 0.3 ≤ (( Do+ do)-( Di+ di))*(n/t) ≤ 0.6.