PROBLEM TO BE SOLVED: To provide a high-strength thin steel sheet that is excellent in a shear-plane delayed-fracture resistance characteristic.SOLUTION: The thin steel sheet has a composition in which, in mass%, C: 0.100 to 0.250%, Si: 0.3% or less, Mn: 0.1 to 2.0%, Al: 0.10% or less, N: 0.010% or less, and V: 0.400 to 1.00%, are contained, and the C, Mn, N and V are contained by adjusting them such that C-(12/51)×(V-(51/14)×N)≥0.013 and Mn/{V-(51/14)×N}≤2.0 are satisfied, and a structure in which the ferrite phase occupying 95% or more in area ratio is the main phase; the main phase ferrite has a phase in which the ratio of average ferrite grain size in a rolling direction dL and a sheet thickness direction dN, dN/dL, is 0.5 or more, and the average grain size is 5 μm or less, and in which, within the grain, a deposition of less than 10 nm is deposited by 1.0×10pieces/μmor more; and thereby a thin steel sheet having high-strength of the yield ratio of 0.80 or more and the tensile strength TS
