Soria has denied all wrongdoing but said he is stepping down to limit any damage to the caretaker government and the People's Party (PP), of which he is a member.
Spain is facing the likelihood of a second general election in June, after the failure of the political parties to form a sustainable coalition government.
Soria of course is not the first to resign because of the Panama Leaks. Icelandic Prime Minister Sigmundur David Gunnlaugsson stepped down earlier this month after documents linked him and his wife to an offshore company.
Soria denied his involvement in an offshore company revealed by the Panama Papers but two Spanish news outlets said they had documents proving he headed an offshore firm with his brother.