A titanium slab made of titanium alloy, the surface of the rolled surface, alpha phase stabilizing elements, either the neutral element, or both are melted by the addition of one or more kinds of elements among has a melt resolidified layer was re-solidified to a depth of 1mm or more ranges, the average value of the total concentration of α-phase stabilizing elements and neutral element in the range to a depth of 1mm is, in the base material α compared to the concentration of the sum of phase stabilizing elements and neutral elements, in mass%, 0.1% or more, which is less than 2.0% higher.