Titania is dissolved in a hydrogen peroxide solution to produce an amorphous titania gel, then the amorphous titania gel and a hydrogen peroxide solution are mixed together to produce an amorphous titania sol, and then an alkali solution is supplied to the solution containing the amorphous titania sol to thereby adjust a pH of the solution to 2 to 10. Even if the obtained solution containing amorphous titania is, for example, left to stand at normal temperature for a long time, gelling or aggregation of titania can be suppressed. That is, it is possible to obtain a titania solution that can maintain the state where fine particles of titania are highly dispersed in the solution, over a long term.