PURPOSE: To produce a high tensile strength galvannealed steel sheet excellent in workability.

CONSTITUTION: In a method for producing a high tensile strength galvannealed steel sheet having 0.2-1.2% Si concentration in the steel, the high tensile strength galvannealed steel sheet excellent in workability can be produced by grinding the surface of a steel sheet to be plated by 0.1-5μm, applying plating to the steel sheet by the use of a hot-dip galvanizing bath having a composition consisting of 0.001-0.2wt.% Si, 0.05-0.20% Al, and the balance Zn with inevitable impurities, and then performing alloying treatment by heating.