PURPOSE: To obtain a cold worked product free from surface roughness by previously applying cold working to a beta titanium alloy stock under specific conditions at the time of recrystallizing the above stock by means of final solution heat treatment to use the above stock in which the recrystallized grains of the stock are remarkably refined.

CONSTITUTION: Prior to the final solution treatment of a beta titanium alloy stock, cold working is applied to this stock at a high draft. For example, when solution heat treatment is carried out at 750-1000°C, cold working is performed at a draft high enough, to form both of the grain boundaries of the grains and respective insides of the grains into nucleation sites, by which the grains of the beta titanium alloy stock can be remarkably refined and, as a result, the cold worked product of the beta titanium alloy free from surface roughness can be obtained when cold working is carried out by using this stock.