Provided is a capsule medical device and a medical system that can alleviate electric power consumed for generating a magnetic field for detecting a position and a posture of the capsule medical device from the outside of a subject. The capsule medical device is a capsule endoscope 100 introduced into a subject and used therein and includes: a power supply unit 123; a capsule detection magnetic field generation unit 126 generating a capsule detection magnetic field for detecting a position and/or a posture of the capsule endoscope 100 from the outside of the subject upon receiving electric power provided by the power supply unit 123; a guiding-magnetic field detector 125 detecting a state of the capsule endoscope 100; and a capsule detection magnetic field controller 127 controlling the power supply to the capsule detection magnetic field generation unit 126 based on an output result of the guiding-magnetic field detector 125.