We report herein a case of advanced hepatocellular carcinoma (HCC) with gastric cancer and rectal cancer. A 68-year-old man was diagnosed with advanced HCC and gastric cancer. At first, he was planned to be treated by trans-catheter arterial chemoembolization (TACE). After TACE, he was diagnosed with rectal cancer by following abdominal computed tomography (CT) and colonoscopy. Then, he was diagnosed with synchronous triple cancer. To avoid bleeding and obstruction, a resection of rectal cancer was performed secondly. After the surgery, he was treated by TACE for three times. HCC was well-controlled, but there remained a small active HCC lesion. Gastric cancer had little progressed, but was still resectable. Finally, we performed a partial hepatectomy and a distal gastrectomy simultaneously. Both of cancer stage and progression-related multimodal treatment is necessary in synchronous cancer.