Antoni Gaudí already wanted the crypt to have a musical instrument that would extol the liturgical celebrations. Unfortunately, he could not see him, as he was installed shortly after his death, in the place indicated by the architect. It was built by the "Fabrica de órganos de Nuestra Señora de Montserrat" in Collbató. The instrument disappeared during the destruction of the furniture elements of the crypt in July 1936.

The Congregation of the Religious of the Sacred Heart had, in its church of the school of the street Diputación, the current instrument and the generous offer to the Sagrada Familia so that, in its crypt, it can have new life and enjoy a greater number of people. This instrument, built in 1896 in Paris, is the only Cavaillé-Coll organ that exists in Catalonia, and fits in a providential way, both by volume and aesthetics and sound in the same chapel where the previous organ was.

In 2021, it was blessed and inaugurated, after the transfer and restoration by the Blancafort Orgueners de Montserrat organery workshop. An independent pedal body was added with three new construction registers.

Additionals: II/I, II/P, I/P, Expressió II, Trèmol II, Appel trompette