To evaluate the effect of naftopidil 75 mg once daily for ureteral double-J (DJ) stent-related discomfort after a ureteroscopic procedure using a multicenter, randomized, double-blinded, placebo-controlled study. 100 patients with indwelled retrograde DJ ureteral stents after ureteroscopic stone removal or retrograde intrarenal surgery (RIRS) were randomized 1:1 to receive either placebo or naftopidil during the stenting period. At the time of stent removal, the Ureteral Stent Symptom Questionnaire (USSQ), the International Prostate Symptom Score and the total amount of used analgesics were reported. Of the 92 patients who completed the study, 49 patients were enrolled in the placebo group, and 43 patients in the naftopidil group. USSQ urinary symptom scores (30.90 vs. 29.23, p = 0.299) and USSQ body pain scores (22.28 vs. 19.58, respectively, p = 0.286) were lower in the naftopidil group than in the placebo group, but the difference was not significant. Multivariate analysis showed that the use of a ureteral access sheath during RIRS was the only significant predictor of postoperative DJ-related pain (OR = 2.736, p = 0.031). The use of naftopidil once daily did not significantly reduce DJ ureteral stent-related discomfort. Larger-scaled prospective studies should be conducted to evaluate the effects of naftopidil on DJ stent-related symptoms and surgeries.