Serratus posterior superior intercostal plane block (SPSIPB) is a newly described truncal block. Here, we aim to share our experience with an SPSIPB catheter for pain management in a 71-year-old woman who underwent a salvage mastectomy and received a continuous infusion of 1 mg/mL bupivacaine solution at 5 mL/h for 48 hours. During follow-up, Numeric Rating Scale scores were <= 4, and Quality of Recovery-15 (QoR-15) scores improved at 48 h. Continuous SPSIPB is effective for postoperative pain management and for improving the QoR in patients undergoing breast surgery.