A clad steel sheet of the present invention comprises a base steel sheet and a cladding material bonded to the base steel sheet, wherein the component composition of the base steel sheet comprises, in terms of % by mass, 0.120 to 0.180% of C, 0.15 to 0.40% of Si, 0.50 to 0.90% of Mn, 0.020% or less of P, 0.010% or less of S, 0.800 to 1.100% of Cu+Ni+Cr (wherein each elemental symbol represents the content of the element), 0.45 to 0.60% of Mo, 0.005 to 0.025% of Nb, 0.005 to 0.050% of Al, 0.0010 to 0.0070% of N and a remainder made up by Fe and unavoidable impurities, wherein the area ratio of bainite at a position corresponding to 1/2 of the thickness of the base steel sheet as observed in the thickness direction is 20% or more, and the average crystal grain diameter of ferrite at a position corresponding to 1/2 of the thickness of the base steel sheet as observed in the thickness direction is 15 μm or less.