High-strength galvanized steel sheet having excellent distinctness of image after painting and manufacturing method therefor

A method of manufacturing a high-strength hot-dip galvanized steel sheet having excellent surface distinctness of image after painting, comprising:

• heating a steel slab at 1100 to 1300° C., the steel slab containing, by mass %, 0.003 to 0.005% of C, 0.05% or less of Si, 0.4 to 1.0% of Mn, 0.04 to 0.06% of P, 0.01% or less of S, 0.005% or less of N, 0.1% or less of S. Al, 0.05 to 0.08% of Mo, 0.005 to 0.03% of Ti, 0.02 to 0.035% of Nb, 0.06 to 0.1% of Cu, 0.0015% of B, and a balance of Fe and inevitable impurities, wherein C, Ti, and Nb satisfy Relationship Formula 1;
• manufacturing a hot-rolled steel sheet by hot-rolling the heated steel slab to a finish-rolling temperature of 920 to 970° C., and then coiling the heated steel slab at a temperature of 600 to 650° C.;
• manufacturing a cold-rolled steel sheet by cold-rolling the coiled hot-rolled steel sheet at a reduction ratio of 70 to 83% after pickling the coiled hot-rolled steel sheet;
• annealing the cold-rolled steel sheet within a temperature range of 760 to 830° C. and then performing hot-dip galvanizing on the cold-rolled steel sheet;
• and
• performing an alloying heat treatment on the hot-dip galvanized steel sheet within a temperature range of 500 to 560° C.
• 0.03≤[(Nb(48/93))+(Ti(93/48))+(C(12/48))]≤0.04 [Relationship Formula]