The present invention addresses the problem of providing a dental unit that ensures appropriate operation of a safety device even if disconnection occurs, and that reduces situations in which treatment is interrupted due to the operation of a dental chair. In the present invention, provided is a safety device 50 that detects unintended contact and restricts the movement and rotation of a movable unit. The safety device is provided with: a sensor 51 for detecting unintended contact； wiring 52 that is led out from the sensor； and a control substrate 53 to which the wiring is connected and which controls the operation of a patient chair on the basis of the sensor and of whether there is wiring disconnect. The sensor includes: a switch 51a that opens and closes according to the presence or absence of unintended contact； at least two positive electrode-side connection parts 51c, 51d that are disposed on the positive electrode-side of the switch； and at least two negative electrode-side connection parts 51e, 51f that are disposed on the negative electrode-side of the switch. A resistor 51b connects one of the positive electrode-side connection parts and one of the negative electrode-side connection parts, and the resistor is disposed in parallel with the switch. The wiring is configured so that at least a total of four wires are lead out respectively from the two positive electrode-side connection parts and the two negative electrode-side connection parts of the sensor.La présente invention concerne une unité dentaire qui garantit le fonctionnement approprié d'un dispositif de sécurité même si une déconnexion se produit, et réduit les situations dans lesquelles le traitement est interrompu en raison du fonctionnement d'un fauteuil dentaire. La présente invention porte plus particulièrement sur un dispositif de sécurité 50 qui détecte un contact involontaire et limite le mouvement et la rotation d'une unité mobile. Le dispositif de sécurité est pourvu des éléments suivants
