Coating agent for electrical steel sheet, manufacturing method therefor and electrical steel sheet coating method using same

A coating agent for an electrical steel sheet, comprising a metal phosphate derivative solution, silica, and chromium oxide, wherein in the metal phosphate derivative solution, the metal phosphate derivative is a single material of a magnesium phosphate derivative or a mixed material of an aluminum phosphate derivative and a magnesium phosphate derivative, in the mixed material of the aluminum phosphate derivative and magnesium phosphate derivative, an amount of the aluminum phosphate derivative is 10 wt % or less (not including 0%),

• wherein in the case that the silica is a mixture of colloid silica and solid silica, the colloid silica is added in an amount of 50 to 250 parts by weight based on 100 parts by weight of the metal phosphate derivative solution, and the solid silica is added in an amount of 5 to 15 parts by weight.