An apparatus for detecting a break in a warp yarn in a loom includes a heald, a heald frame, a carrier rod, a sensor, a controller and a signal line. The heald is made of a resin material for guiding a warp yarn. The heald frame performs a shedding operation of warp yarns and has the carrier rod for supporting a plurality of the healds. The sensor is provided in the heald for sensing a deformation of the heald caused by a tension of the warp yarn and outputting a signal. The controller is provided for determining a condition of the break in the warp yarn based on the signal of the sensor. The signal line electrically connects to the sensor and the controller.