A copper alloy sheet for an electric and electronic part consisting of: Fe 0.01 to 0.50%; and P 0.01 to 0.15%, respectively, and optionally Sn 0.005 to 5.0% and/or Zn 0.005 to 3.0%, and one or more elements of one or more groups selected from the following group A to group D: group A: a total content of 0.0001 to 1.0% of one or more elements selected from Mn, Mg, and Ca; group B: a total content of 0.001 to 1.0% of one or more elements selected from Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt; group C: comprising a total content of 0.0001 to 1.0% of one or more elements selected from Mn, Mg, and Ca, and a total content of 0.001 to 1.0% of one or more elements selected from Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt, respectively, and a total content of 1.0% or less of these elements comprised; and group D: a total content of 0.1% or less of Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B, and misch metal, and the remainder is Cu, wherein the copper alloy sheet has an improved softening resistance by the sheet having a microstructure in which a ratio (I /I) of the X-ray diffraction intensity (I) of Cube orientation from the plane in the sheet surface, to the X-ray diffraction intensity (I) of an orientation other than Cube orientation from the plane, is 0.3 or less, measured by using an X-ray diffraction method. Fe 0.01 to 0.50%; and P 0.01 to 0.15%, respectively, and optionally Sn 0.005 to 5.0% and/or Zn 0.005 to 3.0%, and one or more elements of one or more groups selected from the following group A to group D: group A: a total content of 0.0001 to 1.0% of one or more elements selected from Mn, Mg, and Ca; group B: a total content of 0.001 to 1.0% of one or more elements selected from Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt; group C: comprising a total content of 0.0001 to 1.0% of one or more elements selected from Mn, Mg, and Ca, and a total content of 0.001 to 1.0% of one or more elements selected from Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt, respectively, and a total content of 1.0% or less of these elements comprised; and group D: a total content of 0.1% or less of Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B, and misch metal, and the remainder is Cu, wherein the copper alloy sheet has an improved softening resistance by the sheet having a microstructure in which a ratio (I /I) of the X-ray diffraction intensity (I) of Cube orientation from the plane in the sheet surface, to the X-ray diffraction intensity (I) of an orientation other than Cube orientation from the plane, is 0.3 or less, measured by using an X-ray diffraction method. group A: a total content of 0.0001 to 1.0% of one or more elements selected from Mn, Mg, and Ca; group B: a total content of 0.001 to 1.0% of one or more elements selected from Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt; group C: comprising a total content of 0.0001 to 1.0% of one or more elements selected from Mn, Mg, and Ca, and a total content of 0.001 to 1.0% of one or more elements selected from Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt, respectively, and a total content of 1.0% or less of these elements comprised; and group D: a total content of 0.1% or less of Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B, and misch metal, and the remainder is Cu,