A high strength steel sheet having excellent surface quality and formability with a tensile strength of 980 MPa or more and a TS-El balance of 30000 MPa % or more is provided. A high strength steel sheet comprises: a chemical composition containing C: 0.08% to 0.30%, Si: 2.0% or less, Mn: more than 3.0% and 10.0% or less, P: 0.05% or less, S: 0.01% or less, Al: 1.5% or less, Ti: 0.010% to 0.300%, and N: 0.0020% to 0.0100% in a range satisfying 1.1≤(Ti+Mn1/2/400)/(0.01+5N)≤6.0; and a microstructure including a retained austenite phase and a ferrite phase, wherein a ratio γMn/αMn of an average Mn concentration (γMn) of the retained austenite phase to an average Mn concentration (αMn) of the ferrite phase is 1.5 or more.