Oil pump rotor

Provided is an oil pump rotor that can embody the improvement of noiseless properties and volume effects. When a base circle (bi) of an inner rotor has a diameter (phibi), a first external rolling circle (Di) has a diameter (phiDi), a first internal rolling circle (di) has a diameter (phidi), a base circle (bo) of an outer rotor has a diameter (phibo), a second external rolling circle (Do) has a diameter (phiDo), a second external rolling circle (do) has a diameter (phido), and an amount of eccentricity between the inner rotor and an outer rotor is e, the following formulas are satisfied: phibi = n(phiDi + phidi) and phibo = (n + 1)(phiDo + phido), and either phiDi + phidi = 2e or phiDo + phido = 2e, and furthermore, phiDo>phiDi, and phidi>phido. When a clearance between the inner rotor and the outer rotor is t, in a case of phiDi + phidi = 2e, the following formula is satisfied: 0.3 @ ((phiDo + phido) - (phiDi + phidi ))(n +1)/t @ 0.6. In the case of phiDo + phido = 2e, the following formula is satisfied: 0.