High-strength hot-dipped galvanized steel sheet having excellent surface quality and spot weldability, and manufacturing method therefor

A galvanized steel sheet, comprising:

• a base steel sheet;
• and
• a zinc-based plating layer provided on a surface of the base steel sheet, wherein the base steel sheet includes a first surface layer region corresponding to a depth of 25 μm from an interface between the base steel sheet and the zinc-based plating layer in a thickness direction of the base steel sheet and a second surface layer region adjacent to the first surface layer region and corresponding to a depth of 25 μm to 50 μm in the thickness direction of the base steel sheet, a fraction of ferrite contained in the first surface layer region is 55 area % or more, an average grain size of the ferrite contained in the first surface layer region is 2 to 10 μm, a fraction of ferrite contained in the second surface layer region is 30 area % or more, and an average grain size of ferrite contained in the second surface layer region is 1.35 to 7 μm, an average depth (a) of an internal oxidation layer formed on the base steel sheet is 2 μm or more, a difference (b−c) between an average depth (b) of the internal oxidation layer at an edge portion of a plated steel sheet in a width direction and an average depth (c) of the internal oxidation layer at a center portion of the plated steel sheet in the width direction exceeds zero,
• the average depth (b) of the internal oxidation layer at an edge portion side is an average value of a depth of the internal oxidation layer measured at a point 0.5 cm apart from an edge of the plated steel sheet in a width direction toward a central portion of the plated steel sheet in the width direction of the plated steel sheet and a point 1.0 cm apart from the edge of the plated steel sheet in the width direction toward the central portion of the plated steel sheet in the width direction of the plated steel sheet,
• the average depth (c) of the internal oxidation layer at the central portion is an average value of a depth of the internal oxidation layer measured at a point 15 cm apart from the edge of the plated steel sheet in the width direction toward the central portion of the plated steel sheet in the width direction of the plated steel sheet and a point 30 cm apart from the edge of the plated steel sheet in the width direction toward the central portion of the plated steel sheet in the width direction of the plated steel sheet, and a depth of the internal oxidation layer measured at the center of the plated steel sheet in the width direction, and
• the average depth (a) of the internal oxidation layer formed on the base steel sheet is the average value of the average depth (b) of the internal oxidation layer at the edge portion side and the average depth (c) of the internal oxidation layer at the central portion.