A steel material for a pressure vessel having excellent surface quality and impact toughness, the steel material comprising: by weight percentage (wt%), 0.1 to 0.15% of carbon (C), 0.15 to 0.5% of silicon (Si), 1.2 to 1.8% of manganese (Mn), 0.01% or less, excluding 0%, of phosphorus (P), 0.01% or less, excluding 0%, of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.01 to 0.05% of niobium (Nb), 0.01 to 0.25% of nickel (Ni), 0.1% or less (excluding 0%) of copper (Cu), 0.01 to 0.1% of molybdenum (Mo), 0.01 to 0.05% of vanadium (V), 0.003% or less (excluding 0%) of titanium (Ti), 5 ppm less, excluding 0 ppm, of boron (B), 20 to 100 ppm of nitrogen (N), and a balance of iron (Fe) and other inevitable impurities, and satisfying Relational Expression 1 below, wherein the steel material comprises a composite structure of ferrite and bainitic ferrite as a microstructure wherein when a thickness of the steel material is greater than 35 mm, the steel material comprises ferrite having an area fraction of 40 to 80% and as a balance retained bainitic ferrite as a microstructure, and wherein when a thickness of the steel material is 35 mm or less, the steel material comprises ferrite having an area fraction of 20 to 60%, tempered martensite having an area fraction of 20% or less, including 0 %, and a balance of retained bainitic ferrite as a microstructure, wherein in a 1/4t point, where t refers to a thickness (mm) of the steel material, the tensile strength is 480 MPa or more, and Charpy impact absorption energy at a temperature of -50°C is 150J or more. wherein in a 1/2t point, where t refers to a thickness (mm) of the steel material, tensile strength is 480 MPa or more, and Charpy impact absorption energy at a temperature of -50°C is 100J or more, whereby the Charpy value was determined according to the description, wherein the steel material has a thickness of 10 to 150 mm, whereby ferrite refers to acicular ferrite, 0.5 < Ti + Nb + B / 3.5 N + Cu/Ni < 2.5 where each element refers to a content by wt%. by weight percentage (wt%), 0.1 to 0.15% of carbon (C), 0.15 to 0.5% of silicon (Si), 1.2 to 1.8% of manganese (Mn), 0.01% or less, excluding 0%, of phosphorus (P), 0.01% or less, excluding 0%, of sulfur (S), 0.01 to 0.05% of aluminum (Al), 0.01 to 0.05% of niobium (Nb), 0.01 to 0.25% of nickel (Ni), 0.1% or less (excluding 0%) of copper (Cu), 0.01 to 0.1% of molybdenum (Mo), 0.01 to 0.05% of vanadium (V), 0.003% or less (excluding 0%) of titanium (Ti), 5 ppm less, excluding 0 ppm, of boron (B), 20 to 100 ppm of nitrogen (N), and a balance of iron (Fe) and other inevitable impurities, and satisfying Relational Expression 1 below, wherein the steel material comprises a composite structure of ferrite and bainitic ferrite as a microstructure wherein when a thickness of the steel material is greater than 35 mm, the steel material comprises ferrite having an area fraction of 40 to 80% and as a balance retained bainitic ferrite as a microstructure, and wherein when a thickness of the steel material is 35 mm or less, the steel material comprises ferrite having an area fraction of 20 to 60%, tempered martensite having an area fraction of 20% or less, including 0 %, and a balance of retained bainitic ferrite as a microstructure, wherein in a 1/4t point, where t refers to a thickness (mm) of the steel material, the tensile strength is 480 MPa or more, and Charpy impact absorption energy at a temperature of -50°C is 150J or more. wherein in a 1/2t point, where t refers to a thickness (mm) of the steel material, tensile strength is 480 MPa or more, and Charpy impact absorption energy at a temperature of -50°C is 100J or more, whereby the Charpy value was determined according to the description, wherein the steel material has a thickness of 10 to 150 mm, whereby ferrite refers to acicular ferrite, 0.5 < Ti + Nb + B / 3.5 N + Cu/Ni < 2.5 where each element refers to a content by wt%. <EOS>