We describe the treatment rationale and procedure for a randomized study (J-SONIC; University Hospital Medical Information Network Clinical Trials Registry identification no., UMIN000026799) of carboplatin plus nanoparticle albumin-bound paclitaxel (nab-paclitaxel) with or without nintedanib for patients with advanced non–small cell lung cancer (NSCLC) and idiopathic pulmonary fibrosis (IPF). The study was designed to examine the efficacy and safety of nintedanib administered with carboplatin plus nab-paclitaxel versus carboplatin plus nab-paclitaxel alone in chemotherapy-naive patients with advanced NSCLC associated with IPF. Eligible patients (enrollment target, n = 170) will be randomized at a 1:1 ratio to receive 4 cycles of carboplatin (area under the curve, 6 on day 1) plus nab-paclitaxel (100 mg/m2 on days 1, 8, and 15) administered every 3 weeks either without (arm A) or with (arm B) nintedanib (150 mg twice daily), to be followed in arm B by single-agent administration of nintedanib (150 mg twice daily). The present trial is the first randomized controlled study for the treatment of NSCLC associated with IPF. The goal of the study is to demonstrate that nintedanib combined with carboplatin plus nab-paclitaxel prolongs the interval to acute exacerbation of IPF compared with carboplatin plus nab-paclitaxel alone.