A 65-year-old man was referred to our hospital following repetitive chest pain. Invasive coronary angiography showed an intermediate stenosis of the proximal left anterior descending artery (LAD), and a coronary fistula originating distal to the stenosis draining into the main pulmonary artery. To evaluate the functional abnormality arising from the stenosis and coronary steal due to the fistula, fractional flow reserve (FFR) was measured using a pressure wire with pullback recording. The FFR value was 0.74 at the distal LAD, 0.78 distal to the fistula, 0.81 proximal to the fistula (distal to the stenosis), and abruptly increased to 1.0 proximal to the stenosis. Based on these FFR results, percutaneous coronary intervention was performed to the stenosis. After stent placement, the FFR value improved to 0.87 at the distal LAD, and no abrupt pressure gradient was observed beyond the fistula and the stent. FFR-guided intervention with pullback pressure recording could be a useful and practical method to apply in cases with coronary stenosis complicated by coronary fistula in the same vessel.