An electron-beam welded joint having a welded metal and manufactured by applying an electron-beam welding to a steel material, the steel material having a composition consisting of, by mass %: C: 0.02% to 0.10%; Si: 0.03% to 0.30%; Mn: 1.8% to 2.5%; Ti: 0.005% to 0.015%; N: 0.0020% to 0.0060%; O: 0.0010% to 0.0035%; Mg: 0.0003% to 0.0027%; Ca: 0.0003% to 0.0027%; Nb: 0% to 0.020%; V: 0% to 0.030%; Cr: 0% to 0.50%; Mo: 0% to 0.50%; Cu: 0% to 0.25%; Ni: 0% to 0.50%; B: 0% to 0.0030%; Al: limited to 0.015% or less; P: limited to 0.015% or less; and S: limited to 0.010% or less, with a balance consisting of iron and inevitable impurities, wherein an amount of Mg and Ca contained in the composition of the steel material satisfies 0.0006% ≤ Mg + Ca ≤ 0.0040% in mass %, a total amount in mass% of Cr, Mo, Cu, and Ni in the composition of the steel is 0.70 or less, and an index value CeEBB, which is the index of hardenability after electron-beam welding of steel material, obtained by substituting the composition of the steel material into the following Formula 1 is 0.42% or more and 0.65% or less, a C/CeEBB, which is a ratio of the amount of C in the steel material by mass% relative to the index value CeEBB, falls in the range of 0.02 to 0.15, number of oxides having an equivalent circle diameter of 1.0 μm or more is 20 pieces/mm 2 or less at a thickness center portion in cross-section along a thickness direction of the steel material, number of oxides containing Mg of 7% or more and having an equivalent circle diameter of 0.05 μm or more and less than 0.5 μm is 1 × 10 3 to 1 × 10 5 pieces/mm 2 at the thickness center portion, the number of the oxides containing Mg of 7% or more and having an equivalent circle diameter of 0.05 μm or more and less than 0.5 μm being measured by using FE-TEM at a magnification of 10000-fold to 1000000-fold, the welded metal has a composition including, by mass %: C: 0.02% to 0.10%; Si: 0.03% to 0.30%; Mn: 1.2% to 2.4%; Ni: 1.0% to 2.3%; Ti: 0.005% to 0.015%; N: 0.0020% to 0.0060%; O: 0.0004% to 0.0020%; Mg: 0.0003% to 0.0027%; Ca: 0.0003% to 0.0027%; Nb: 0% to 0.020%; V: 0% to 0.030%; Cr: 0% to 0.50%; Mo: 0% to 0.50%; Cu: 0% to 0.25%; B: 0% to 0.0030%; Al: limited to 0.015% or less; P: limited to 0.015% or less; and S: limited to 0.010% or less, with a balance consisting of iron and inevitable impurities, wherein an amount of Mg and Ca contained in the composition of the welded metal satisfies 0.0006% ≤ Mg + Ca ≤ 0.0040% in mass %, and an index value of CeEBW, which is the index of hardenability after electron-beam welding of welded metal, obtained by substituting the composition of the welded metal into the following Formula 2 is 0.56% or more and 0.73% or less, CeEBB = C + 1 / 4 Mn + 1 / 15 Cu + 1 / 15 Ni + 1 / 5 Cr + 1 / 5 Mo + 1 / 5 V where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements contained in the composition of the steel material. CeEBW = C + 1 / 4 Mn + 1 / 15 Cu + 1 / 15 Ni + 1 / 5 Cr + 1 / 5 Mo + 1 / 5 V where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements contained in the composition of the welded metal. C: 0.02% to 0.10%; Si: 0.03% to 0.30%; Mn: 1.8% to 2.5%; Ti: 0.005% to 0.015%; N: 0.0020% to 0.0060%; O: 0.0010% to 0.0035%; Mg: 0.0003% to 0.0027%; Ca: 0.0003% to 0.0027%; Nb: 0% to 0.020%; V: 0% to 0.030%; Cr: 0% to 0.50%; Mo: 0% to 0.50%; Cu: 0% to 0.25%; Ni: 0% to 0.50%; B: 0% to 0.0030%; Al: limited to 0.015% or less; P: limited to 0.015% or less; and S: limited to 0.010% or less, C: 0.02% to 0.10%; Si: 0.03% to 0.30%; Mn: 1.2% to 2.4%; Ni: 1.0% to 2.3%; Ti: 0.005% to 0.015%; N: 0.0020% to 0.0060%; O: 0.0004% to 0.0020%; Mg: 0.0003% to 0.0027%; Ca: 0.0003% to 0.0027%; Nb: 0% to 0.020%; V: 0% to 0.030%; Cr: 0% to 0.50%; Mo: 0% to 0.50%; Cu: 0% to 0.25%; B: 0% to 0.0030%; Al: limited to 0.015% or less; P: limited to 0.015% or less; and S: limited to 0.010% or less,