TABLEWARE MADE OF TITANIUM OR TITANIUM ALLOY AND SURFACE TREATING METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a tableware made of titanium and a titanium alloy excellent in appearance quality without damaging its beautiful sight and to provide a surface treating method therefor. SOLUTION: The inside of a vacuum tank is deposited with a tableware 100 made of titanium or a titanium alloy, which is heated and subjected to annealing treatment, thereafter, a gaseous mixture essentially consisting of nitrogen 104 and contg. a trace amount of oxygen component 105 is introduced into the vacuum tank, the inside of the vacuum tank is heated at 700 to 800 deg.C for a prescribed time in a prescribed pressure-reduced state, nitrogen and oxygen are diffusively entered into solid solution from the surface of the tableware made of titanium or a titanium alloy to the inside, and, after that, the tableware made of titanium or a titanium alloy is cooled to an ordinary temperature. As a result, a surface hardened layer 101 containing a first hardened layer 102 in which nitrogen and oxygen are entered into solid solution and a second hardened layer 103 in which oxygen is entered into solid solution is formed on the tableware made of titanium or a titanium alloy.