An endoscope system includes a capsule endoscope that includes an imaging section, a first processing section that causes the imaging section to operate in a first mode or a second mode, and a first communication section that transmits the captured images to an external device, and the external device that includes a second processing section that outputs a mode switch instruction based on the captured images, and a second communication section that transmits the mode switch instruction, wherein the first processing section causes the imaging section to operate in the second mode from a halfway position of the small intestine, and also operate in the second mode in the large intestine based on the mode switch instruction.