There are herein disclosed an L-type zeolite catalyst which is obtainable by supporting a platinum component, one or more halogen components and one or more metal components selected from the group Ib of the periodic table on an L-type zeolite, the support amount of one or more metal components selected from the group Ib being in the range of 0.001 to 3% by weight based on the total weight of the catalyst in terms of the metal, a molar ratio of one or more metal components selected from the group Ib/platinum being in the range of 0.01 to 1; and a method for producing aromatic hydrocarbons or a gasoline having a high octane number which comprises the step of bringing one or more fractions selected from a C6 fraction, a C7 fraction, and a C8.sup.+ fraction into contact with this catalyst. According to the present invention, there are provided a catalyst containing an L-type zeolite as a carrier which is desirable as a catalyst for the production of aromatic hydrocarbons or a gasoline having a high octane number and which can inhibit a cracking activity and the formation of coke and can improve an aromatic selectivity and a liquid yield.