High-strength steel having excellent resistance to sulfide stress cracking, and method for manufacturing same

A high-strength steel material having excellent resistance to sulfide stress cracking, comprising:

• in % by weight, carbon (C):
• 0.02 to 0.06%, silicon (Si):
• 0.1 to 0.5%, manganese (Mn):
• 0.8 to 1.8%, phosphorus (P):
• 0.03% or less, sulfur (S):
• 0.003% or less, aluminum (Al):
• 0.06% or less, nitrogen (N):
• 0.01% or less, niobium (Nb):
• 0.005 to 0.08%, titanium (Ti):
• 0.005 to 0.05%, and calcium (Ca):
• 0.0005 to 0.005%;
• at least one of nickel (Ni):
• 0.05 to 0.3%, chromium (Cr):
• 0.05 to 0.3%, molybdenum (Mo):
• 0.02 to 0.2% and vanadium (V):
• 0.005 to 0.1%;
• and Fe and unavoidable impurities as balances,
• wherein the Ca and S satisfy relational formula 1:
• 0.5≤Ca/S≤5.0, where each element refers to weight content, and
• a difference between a hardness value of a surface layer portion and a hardness value of a central portion (surface layer portion hardness−center portion hardness) is 20 Hv or less of Vickers hardness.