Each autonomous region has its own regulations with regards to access to public areas, even if privately owned. In general, service dogs that assist a blind person should be accepted everywhere, but the regulations vary with regards to other assitance dogs, or dogs or puppies in training.
Here´s a link to the information provided by the ONCE, the largest foundation in Spain, originally for those handicapped by diminished eyesight.
In the article there´s a link to the regulations in all Spanish Autonomous regions. In Spanish of course.
Additional info for Andalucia, a very recent law that regulates access for assistance dogs.
¨Ley 4/2017, de 25 de septiembre, de los Derechos y la Atención a las Personas con Discapacidad en Andalucía¨
Artículo 52. Perros de asistencia.
La Administración de la Junta de Andalucía promoverá la utilización de perros de asistencia para facilitar la movilidad y autonomía de las personas con discapacidad que requieran este tipo de apoyo, garantizando que se permita su libre acceso, en la forma que se determine, a todos los lugares, alojamientos, establecimientos, locales, transportes y demás espacios de uso público sin que ello conlleve gasto adicional alguno para dichas personas.
¨ Law 4/2017, of September 25, on the Rights and Care of Persons with Disabilities in Andalusia¨
Article 52. Assistance dogs.
The Administration of the Junta de Andalucía will promote the use of assistance dogs to facilitate the mobility and autonomy of people with disabilities that require this type of support, guaranteeing that their free access, in the way that is determined, is allowed to all places, accommodations, establishments, premises, transports and other spaces for public use without incurring any additional expense for said persons”.