In order to increase performances of an iron oxide-potassium oxide system catalyst to be used for an alkyl aromatic hydrocarbon dehydrogenation reaction in the presence of steam, there is provided an alkyl aromatic hydrocarbon dehydrogenation catalyst wherein a little amount of titanium oxide is added by the mixing and kneading method or by the preceding addition to iron oxide in the production of the iron oxide-potassium oxide system catalyst to be used for the alkyl aromatic hydrocarbon dehydrogenation reaction in the presence of steam. The iron oxide-potassium oxide system catalyst is allowed to contain a little amount of titanium oxide, whereby an activity can be remarkably increased, as well as a selectivity in the same conversion ratio can also be improved in the alkyl aromatic hydrocarbon dehydrogenation reaction, and further the obtained catalyst exhibits stable performances with time on stream.