Of wooden construction with a single-step hull, with pilot and observer/gunner in tandem open cockpits in the bow, the S.57 was powered by a single 186 kW (249 hp) Isotta-Fraschini V.6. The observer had a single ring-mounted 7.7 mm (0.303 in) machine gun.
Eighteen S.57s were accepted by Regia Aeronautica in 1925 and used as trainers.
A sole S.57bis (improved) was built, with a 224 kW (300 hp) Hispano-Suiza Type 42 engine.