When producing an aromatic hydrocarbon by a contact reaction of a lower hydrocarbon with a catalyst, the aromatic hydrocarbon is produced stably for a long time while maintaining a high aromatic hydrocarbon yield. In a process for producing an aromatic hydrocarbon by being equipped with a reaction step for obtaining the aromatic hydrocarbon by a contact reaction of a lower hydrocarbon with a catalyst and a regeneration step for regenerating the catalyst used in this reaction step, and by repeating the reaction step and the regeneration step, yield of the aromatic hydrocarbon is calculated at constant intervals of time. A yield as the standard is set up from this calculated yield. Based on the change of yield relative to this standard, the regeneration time of the regeneration step is prolonged. A threshold value is set up in the change of yield. In case that the change of yield of the aromatic hydrocarbon has been lower than the threshold value in the reaction step, the regeneration time of the regeneration step is prolonged.