This surface-treated steel includes surface-treated steel comprising:



a steel sheet;
a plated layer including zinc formed on the steel sheet; and
a film formed on the plated layer,
wherein the film has a thickness of 100 nm or more and 1000 nm or less,
wherein the film includes:
an amorphous phase A containing Si, C, O, P, Zn, and V, and one or two or more kinds selected from the group consisting of Ti, Zr, and Al as constituent elements, wherein Zn/Si, which is a peak intensity ratio between Zn and Si, is 1.0 or more, and V/P, which is a mass ratio between V and P, is 0.050 to 1.000 when analysis is performed by EDS; and
an amorphous phase B containing Si, O, and Zn, wherein the amorphous phase B has a Zn/Si ratio of less than 1.0, the Zn/Si ratio is a peak intensity ratio between Zn and Si when analysis is performed by EDS,
a Zn content of the amorphous phase A is 10 mass % or less, and
in a cross section in a thickness direction, a percentage of a length of an interface between the plated layer and the amorphous phase B to a length of an interface between the plated layer and the film is 30% or more.