Marquis of Casa Irujo () is a hereditary title of Spanish nobility. It was created on 8 March 1803 by King Charles IV of Spain in favor of Carlos MartÃÂnez de Irujo, the Spanish minister to the United States from 1796 to 1807.
On 24 December 1890, King Alfonso XIII of Spain granted the accompanying dignity of Grandee to the third marquis, Carlos MartÃÂnez de Irujo y del Alcázar.
The name of the marquisate refers to the surname of the first holder.