A new and distinct plum tree variety, Prunus salicina, cv. ‘Suplumfortyseven’ is characterized by mid-season ripening fruit having a dark red flesh, nearly black skin, and a semi-free stone. The fruit is medium in sugar and has medium acidity. The fruit of the new variety ‘Suplumfortyseven’ is also abundant in juice and has a mildly sweet flavor. The new variety ripens before ‘Joanna Red’ (U.S. Plant Pat. No. 10,385) and harvest is later than for ‘Suplumeleven’ (U.S. Plant Pat. No. 4,902).