Subclinical stricture after esophageal endoscopic submucosal dissection (ESD) makes the detection and re-ESD of metachronous lesions difficult. This study aimed to investigate the effectiveness of prophylactic steroid use after esophageal ESD for mucosal defects with a circumference less than 75% for the prevention of symptomatic and asymptomatic stricture. In 80 retrospectively enrolled patients, we collected paired endoscopic images of a mucosal defects immediately after resection and a scar thereafter. After calculating circumference by image analysis software, all patients were classified into three groups in reference to mucosal defect circumference (MDC; ≤ 50%, 50-75%, ≥ 75%). Frequency of steroid use and symptomatic stricture were compared, and in < 75% MDC patients, a degree of asymptomatic stricture with or without steroid was compared by calculating a scar contraction rate (SCR). In the ≤ 50% (43 patients), 50-75% (27 patients) and ≥ 75% (10 patients) MDC groups, steroids were used in 12%, 59% and 100%, respectively, and symptomatic stricture occurred in 0%, 7% and 40%, respectively. In < 75% MDC patients, SCR in the steroid cohort was significantly lower than that in the nonsteroid cohort (42% vs. 65%, p = 0.002). No steroid-related adverse events occurred. Steroid use even for mucosal defects with < 75% circumference appears effective for the reduction of the risk on both symptomatic and asymptomatic stricture after esophageal ESD.