The present invention provides a porous titanium oxide having improved ultraviolet protection ability, usability, and transparency in the visible region and a process for producing thereof. The porous titanium oxide powder according to the present invention can be obtained by adding an alkali to a titanium salt solution containing a polyalcohol and then thermally hydrolyzing the solution. In addition, it is possible that after the addition of the alkali, an acid is further added to the solution and then the thermal hydrolysis is conducted, or that after thermal hydrolysis, further heat treatment with an acid is conducted. A porous titanium oxide has a mean particle size of 0.01 to 1.0 μm and a specific surface area of 50 m2/g or more.