An international with Spain, Castro played at the World Cup in 1978 and 1982, as well as the European Championship in 1980. He scored eight goals in 35 appearances for the national side.
Castro tún kópa fún orílẹ̀-èdè rè, Spain nínú ìdíje bọ́ọ̀lù àgbááyé lọ́dún 1978 àti 1982, bákan náà ló tún kópa nínú ìdíje European Championship lọ́dún 1980. Ó gbá àmì-ayò mẹ́jọ wọlé nínú ìfẹsẹ̀wọnsẹ̀ márùnlélọ́gbọ̀n tí ó gbá fún orílẹ̀-èdè Spain.