To provide a composite ferrite core and a noise current absorption tool having a high noise countermeasure effect in a wide frequency band.

A composite ferrite core 1 includes: a first ferrite core 7 having a first through-hole 11; and a second ferrite core 9 which has a second through-hole 13 and whose magnetic permeability is lower than that of the first ferrite core 7. The ratio between a thickness L1 of the first through-hole 11 in the axial direction in the first ferrite core 7 and a thickens L2 of the second through hole 13 in the axial direction in the second ferrite core 9 is in a range of 6:4 to 9:1.