We report a case of laryngeal cancer with multiple lung metastases that maintained a complete response (CR) for 18 months after discontinuing nivolumab treatment, with colitis developing 5 months after drug discontinuation. A 65-year-old man was diagnosed with T3N2cM0 stage IVA right supraglottic squamous cell carcinoma that progressed after 1 course of TPF (cisplatin, docetaxel, and 5-fluorouracil) as induction chemotherapy. He underwent total laryngectomy, bilateral neck dissection, pharyngeal reconstruction with anterolateral thigh flap, and creation of a permanent tracheostoma; extranodal extension was detected in the right cervical lymph node metastasis, and the patient underwent adjuvant radiotherapy. Multiple lung metastases occurred during radiotherapy, and the patient was deemed platinum refractory; nivolumab treatment was thus initiated. The tumor proportion score for programmed death-ligand 1-evaluated via antibody testing of the laryngeal tumor-was <1. The patient received 240 mg/body nivolumab every 2 weeks; a computed tomography performed after course 16 of nivolumab treatment confirmed a CR. He exhibited grade 2 thyroid dysfunction, grade 1 interstitial pneumonia, and grade 2 colitis after 6, 7, and 14 months of receiving nivolumab, respectively; treatment was discontinued as despite maintaining a CR, interstitial pneumonia occurred twice. Colitis appeared 5 months after nivolumab discontinuation; nevertheless, a CR was maintained after 18 months.