Background Optimal maintenance therapy for lung squamous cell carcinoma (SCC) has not been established. The aim of this study was to evaluate the efficacy and safety of switch maintenance therapy with S-1, an oral fluoropyrimidine, after induction therapy with carboplatin and nanoparticle albumin-bound paclitaxel (nab-paclitaxel) in chemotherapy-naïve patients with advanced SCC. Methods Chemotherapy-naïve patients with advanced SCC received induction therapy with four cycles of carboplatin (at an area under the curve of 6, day 1 of a 28-day cycle) and nab-paclitaxel (100 mg/kg, days 1, 8, and 15). Patients who achieved disease control after induction therapy received maintenance therapy with S-1 (80 mg/m, days 1-14 of a 21-day cycle) until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS) from the start of maintenance therapy. Results Seventy-two patients with SCC were enrolled to the study. After four cycles of induction therapy, 35 (48.6%) patients achieved disease control, and 31 (43.1%) of these patients received maintenance therapy. Median PFS from the start of maintenance therapy was 3.0 months (95% confidence interval: 2.1-3.8 months). The most common toxicities of grade 3 or higher during maintenance therapy were nausea (13.3%), neutropenia (10.0%), and diarrhea (6.7%). Conclusions Switch maintenance therapy with S-1 after induction therapy with carboplatin and nab-paclitaxel was associated with moderate efficacy and acceptable safety and may represent a feasible treatment option for patients with advanced SCC.