The heart rate of a subject can be measured on a regular basis during the subject's daily performance without causing the subject to take trouble to wear a special device or to feel bothersome to keep wearing a special device. A heart rate measurement system includes an intraoral electrode, a hand electrode, and a detection unit. The intraoral electrode is installed in a head portion with implanted brush hair of a toothbrush and comes into contact with an intraoral region of the subject. The hand electrode is installed in a grip of the toothbrush and comes into contact with the subject's hand. The detection unit detects the subject's heart rate. Based on signals from the intraoral electrode and hand electrode, the detection unit derives a potential difference between the intraoral region and the hand and, based on the potential difference, collects heart rate data on the subject.
