Provided is a method for efficiently producing alkoxysilanes that are useful as various functional chemicals. In order to produce alkoxysilanes efficiently, an ethoxy- or methoxysilane and an alcohol are caused to react using, as a catalyst, for instance an inorganic solid acid having a regular-pore and/or layered structure. Zeolites, montmorillonites or the like can be used as the inorganic solid acid. When a zeolite is used as the catalyst, the silica/alumina ratio of the zeolite ranges preferably from 5 to 1000. The reaction can be promoted through irradiation of microwaves.