A method for manufacturing a high strength steel sheet having excellent formability, the method comprising hot-rolling a steel slab having a chemical composition containing, by mass%, C: 0.03% or more and 0.35% or less, Si: 0.5% or more and 3.0% or less, Mn: 3.5% or more and 10.0% or less, P: 0.1% or less, S: 0.01% or less, N: 0.008% or less, optionally Al: 0.01% or more and 2.5% or less, optionally at least one chemical element selected from Cr: 0.05% or more and 1.0% or less, V: 0.005% or more and 0.5% or less, Mo: 0.005% or more and 0.5% or less, Ni: 0.05% or more and 1.0% or less, and Cu: 0.05% or more and 1.0% or less, optionally at least one chemical element selected from Ti: 0.01% or more and 0.1% or less, Nb: 0.01% or more and 0.1% or less, and B: 0.0003% or more and 0.0050% or less, optionally at least one chemical element selected from Ca: 0.001% or more and 0.005% or less and REM: 0.001% or more and 0.005% or less, optionally Mg: 0.0005% or more and 0.0100% or less, optionally Ta: 0.0010% or more and 0.1000% or less, optionally Sn: 0.0020% or more and 0.2000% or less and/or Sb: 0.0020% or more and 0.2000% or less, and the balance comprising Fe and inevitable impurities, coiling the hot − rolled steel sheet at a temperature range of the Ar 1 transformation point to the Ar 1 transformation point + the Ar 3 transformation point − the Ar 1 transformation point / 2, optionally holding the coiled steel sheet at a temperature range of the Ar 1 transformation point to the Ar 1 transformation point + the Ar 3 transformation point − the Ar 1 transformation point / 2 for 5 hours or more, cooling the coiled steel sheet down to 200°C or lower, heating and holding the cooled steel sheet at a temperature range of the Ac 1 transformation point - 200°C to the Ac 1 transformation point for 30 minutes or more, pickling the heated steel sheet, cold-rolling the pickled steel sheet under the condition that the rolling reduction is 20% or more, heating and holding the cold − rolled steel sheet at a temperature range of the Ac 1 transformation point to the Ac 1 transformation point + the Ac 3 transformation point − the Ac 1 transformation point / 2 for 30 seconds or more, and optionally cooling the heated steel sheet down to a temperature of 200 °C or lower and heating and holding the cooled steel sheet at a temperature range of the Ac 1 transformation point to the Ac 1 transformation point + the Ac 3 transformation point − the Ac 1 transformation point / 2 for 10 seconds or more. C: 0.03% or more and 0.35% or less, Si: 0.5% or more and 3.0% or less, Mn: 3.5% or more and 10.0% or less, P: 0.1% or less, S: 0.01% or less, N: 0.008% or less, optionally Al: 0.01% or more and 2.5% or less, optionally at least one chemical element selected from Cr: 0.05% or more and 1.0% or less, V: 0.005% or more and 0.5% or less, Mo: 0.005% or more and 0.5% or less, Ni: 0.05% or more and 1.0% or less, and Cu: 0.05% or more and 1.0% or less, optionally at least one chemical element selected from Ti: 0.01% or more and 0.1% or less, Nb: 0.01% or more and 0.1% or less, and B: 0.0003% or more and 0.0050% or less, optionally at least one chemical element selected from Ca: 0.001% or more and 0.005% or less and REM: 0.001% or more and 0.005% or less, optionally Mg: 0.0005% or more and 0.0100% or less, optionally Ta: 0.0010% or more and 0.1000% or less, optionally Sn: 0.0020% or more and 0.2000% or less and/or Sb: 0.0020% or more and 0.2000% or less, and the balance comprising Fe and inevitable impurities, coiling the hot − rolled steel sheet at a temperature range of the Ar 1 transformation point to the Ar 1 transformation point + the Ar 3 transformation point − the Ar 1 transformation point / 2, optionally holding the coiled steel sheet at a temperature range of the Ar 1 transformation point to the Ar 1 transformation point + the Ar 3 transformation point − the Ar 1 transformation point / 2 for 5 hours or more, cooling the coiled steel sheet down to 200°C or lower, heating and holding the cooled steel sheet at a temperature range of the Ac 1 transformation point - 200°C to the Ac 1 transformation point for 30 minutes or more, pickling the heated steel sheet, cold-rolling the pickled steel sheet under the condition that the rolling reduction is 20% or more, heating and holding the cold − rolled steel sheet at a temperature range of the Ac 1 transformation point to the Ac 1 transformation point + the Ac 3 transformation point − the Ac 1 transformation point / 2 for 30 seconds or more, and optionally cooling the heated steel sheet down to a temperature of 200 °C or lower and heating and holding the cooled steel sheet at a temperature range of the Ac 1 transformation point to the Ac 1 transformation point + the Ac 3 transformation point − the Ac 1 transformation point / 2 for 10 seconds or more.