<b><i>Background:</i></b> There has been no study so far on gemcitabine continuous maintenance therapy targeting only squamous non-small-cell lung cancer (NSCLC) patients. This study aimed to assess the efficacy and safety of cisplatin plus gemcitabine followed by maintenance gemcitabine for chemotherapy- naïve Japanese patients with advanced squamous NSCLC. <b><i>Methods:</i></b> The patients received 4 cycles of gemcitabine (1,000 mg/m<sup>2</sup>, days 1 and 8) and cisplatin (80 mg/m<sup>2</sup>, day 1) every 3 weeks, followed by gemcitabine alone as maintenance therapy every 3 weeks until disease progression or unacceptable toxicity. The primary end point of the study was progression-free survival (PFS) from the date of registration. <b><i>Results:</i></b> From May 2013 to October 2018, 26 patients were enrolled, and 25 patients received ≥1 cycle of planned treatment. Eighteen patients (69.2%) received 4 cycles of cisplatin plus gemcitabine, and 16 patients (61.5%) received ≥1 cycle of maintenance gemcitabine. The median PFS from the date of registration was 5.3 months (95% CI 2.9–7.3 months). In 16 patients who received ≥1 cycle of maintenance gemcitabine, the median PFS from the date of maintenance gemcitabine initiation was 3.8 months (95% CI 2.3–5.2 months). Their median overall survival from the date of registration was 11.9 months (95% CI 7.5–26.5 months). During the maintenance therapy, adverse events (AEs) were mostly Common Terminology Criteria for AE grade 1. <b><i>Conclusions:</i></b> While this trial did not meet the primary endpoint, the sufficient efficacy and feasibility of gemcitabine maintenance therapy were suggested.