Marquess of Casa Irujo (Spanish: Marqués de Casa Irujo) is a hereditary title of Spanish nobility.

[1] It was created on 8 March 1803 by King Charles IV of Spain in favor of Carlos Martínez de Irujo, the Spanish minister to the United States from 1796 to 1807.

[2] On 24 December 1890, King Alfonso XIII of Spain granted the accompanying dignity of Grandee to the third marquis, Carlos Martínez de Irujo y del Alcázar.

The name of the marquessate refers to the surname of the first holder.