An AC superconducting cable with an insulating layer on the external circumference of a conductor, and wherein: the insulating layer includes a first insulating layer, a second insulating layer and a third insulating layer, from the inside layer to the outside layer; the insulating layer is impregnated with liquid nitrogen; the product of the dielectric constant ∈1 of the first insulating layer and the dielectric loss tangent tan δ1 and the product of the dielectric constant ∈2 of the second insulating layer and the dielectric loss tangent tan δ2 fulfilling the relationship ∈1×tan δ1>∈2×tan δ2; and the product of the dielectric constant ∈2 of the second insulating layer and the dielectric loss tangent tan δ2 and the product of the dielectric constant ∈3 of the third insulating layer and the dielectric loss tangent tan δ3 fulfilling the relationship ∈2×tan δ2