An electric resistance welded steel pipe for a linepipe, the steel pipe comprising: a base metal portion; and an electric resistance welded portion, wherein the base metal portion has a chemical composition consisting of, in terms of % by mass: 0.03% or more and less than 0.10% of C, from 0.30 to 1.00% of Mn, from 0.005 to 0.050% of Ti, from 0.010 to 0.100% of Nb, from 0.001 to 0.020% of N, from 0.010 to 0.500% of Si, from 0.001 to 0.100% of Al, from 0 to 0.030% of P, from 0 to 0.010% of S, from 0 to 0.50% of Mo, from 0 to 0.50% of Cu, from 0 to 0.50% of Ni, from 0 to 0.50% of Cr, from 0 to 0.10% of V, from 0 to 0.0100% of Ca, from 0 to 0.0100% of REM, and a balance consisting of Fe and impurities, wherein CNeq, represented by Formula, is from 0.12 to 0.25, a ratio of a content of Mn with respect to a content of Si is 1.8 or more, and LR, represented by Formula, is 0.25 or more: CNeq = C + Mn / 6 + Cr / 5 + Ni + Cu / 15 + Nb + Mo + V LR = 2.1 C + Nb / Mn wherein, in Formulae and, each element symbol represents a content of each element in % by mass, wherein the base metal portion has a metallographic microstructure in which: a first phase composed of ferrite has an area ratio of from 80 to 98%, a second phase, which is a balance, contains at least one of pearlite or bainite; an area ratio of martensite with respect to a total area of the second phase is less than 1%; and a value obtained by subtracting a hardness of the first phase from a hardness of the second phase is from 50 to 100 Hv, wherein the electric resistance welded steel pipe has: a yield strength in a pipe axis direction of from 360 to 600 MPa; a tensile strength in the pipe axis direction of from 465 to 760 MPa; and a yield ratio in the pipe axis direction of 0.90 or less, wherein each of the base metal portion and the electric resistance welded portion has a Charpy absorbed energy at 0°C of 100 J or more, and wherein a yield elongation of the electric resistance welded steel pipe, as measured in a tensile test in the pipe axis direction, is less than 0.2%, wherein the metallographic microstructure, hardness, yield strength, tensile strength, yield ratio, Charpy absorbed energy, and yield elongation are determined in accordance with the description. a base metal portion; and an electric resistance welded portion, wherein the base metal portion has a chemical composition consisting of, in terms of % by mass: 0.03% or more and less than 0.10% of C, from 0.30 to 1.00% of Mn, from 0.005 to 0.050% of Ti, from 0.010 to 0.100% of Nb, from 0.001 to 0.020% of N, from 0.010 to 0.500% of Si, from 0.001 to 0.100% of Al, from 0 to 0.030% of P, from 0 to 0.010% of S, from 0 to 0.50% of Mo, from 0 to 0.50% of Cu, from 0 to 0.50% of Ni, from 0 to 0.50% of Cr, from 0 to 0.10% of V, from 0 to 0.0100% of Ca, from 0 to 0.0100% of REM, and a balance consisting of Fe and impurities, 0.03% or more and less than 0.10% of C, from 0.30 to 1.00% of Mn, from 0.005 to 0.050% of Ti, from 0.010 to 0.100% of Nb, from 0.001 to 0.020% of N, from 0.010 to 0.500% of Si, from 0.001 to 0.100% of Al, from 0 to 0.030% of P, from 0 to 0.010% of S, from 0 to 0.50% of Mo, from 0 to 0.50% of Cu, from 0 to 0.50% of Ni, from 0 to 0.50% of Cr, from 0 to 0.10% of V, from 0 to 0.0100% of Ca, from 0 to 0.0100% of REM, and a balance consisting of Fe and impurities, wherein CNeq, represented by Formula, is from 0.12 to 0.25, a ratio of a content of Mn with respect to a content of Si is 1.8 or more, and LR, represented by Formula, is 0.25 or more: CNeq = C + Mn / 6 + Cr / 5 + Ni + Cu / 15 + Nb + Mo + V LR = 2.1 C + Nb / Mn wherein, in Formulae and, each element symbol represents a content of each element in % by mass, wherein the base metal portion has a metallographic microstructure in which: a first phase composed of ferrite has an area ratio of from 80 to 98%, a second phase, which is a balance, contains at least one of pearlite or bainite; an area ratio of martensite with respect to a total area of the second phase is less than 1%; and a value obtained by subtracting a hardness of the first phase from a hardness of the second phase is from 50 to 100 Hv, a first phase composed of ferrite has an area ratio of from 80 to 98%, a second phase, which is a balance, contains at least one of pearlite or bainite; an area ratio of martensite with respect to a total area of the second phase is less than 1%; and a value obtained by subtracting a hardness of the first phase from a hardness of the second phase is from 50 to 100 Hv, wherein the electric resistance welded steel pipe has: a yield strength in a pipe axis direction of from 360 to 600 MPa; a tensile strength in the pipe axis direction of from 465 to 760 MPa; and a yield ratio in the pipe axis direction of 0.90 or less, a yield strength in a pipe axis direction of from 360 to 600 MPa; a tensile strength in the pipe axis direction of from 465 to 760 MPa; and a yield ratio in the pipe axis direction of 0.90 or less, wherein each of the base metal portion and the electric resistance welded portion has a Charpy absorbed energy at 0°C of 100 J or more, and wherein a yield elongation of the electric resistance welded steel pipe, as measured in a tensile test in the pipe axis direction, is less than 0.2%, wherein the metallographic microstructure, hardness, yield strength, tensile strength, yield ratio, Charpy absorbed energy, and yield elongation are determined in accordance with the description.