A torque measuring device for a flywheel, the torque measuring device adapted to be mounted on a frame of an exercise bike which has the flywheel, a wheel shaft mounted through the flywheel, and a transmission mechanism driving the flywheel, the torque measuring device adapted to be connected to the flywheel, the wheel shaft, and the transmission mechanism, and the torque measuring device comprising: a base rotatably mounted on the wheel shaft and having a combination portion; and a connection portion attached to the combination portion and having an outer peripheral surface; and a transmission portion disposed next to the connection portion and connected to the transmission mechanism; and a measuring assembly mounted on the wheel shaft and the base and having a magnet mounted on the wheel shaft; and multiple torque measuring apparatuses mounted on and arranged around the outer peripheral surface of the connection portion of the base; and a communication module mounted on the combination portion of the base and receiving and outputting measurement data measured by the measuring assembly; and a power module mounted on the combination portion of the base and providing electricity to the communication module and the multiple torque measuring apparatuses, and characterized in that: the combination portion has a first side fixed to the flywheel; and a second side opposite to the first side; the connection portion is attached to the first side of the combination portion; the communication module is mounted on the second side of the combination portion without being shielded by the flywheel; and the power module is mounted on the second side of the combination portion without being shielded by the flywheel. a base rotatably mounted on the wheel shaft and having a combination portion; and a connection portion attached to the combination portion and having an outer peripheral surface; and a transmission portion disposed next to the connection portion and connected to the transmission mechanism; and a combination portion; and a connection portion attached to the combination portion and having an outer peripheral surface; and a transmission portion disposed next to the connection portion and connected to the transmission mechanism; and a measuring assembly mounted on the wheel shaft and the base and having a magnet mounted on the wheel shaft; and multiple torque measuring apparatuses mounted on and arranged around the outer peripheral surface of the connection portion of the base; and a magnet mounted on the wheel shaft; and multiple torque measuring apparatuses mounted on and arranged around the outer peripheral surface of the connection portion of the base; and a communication module mounted on the combination portion of the base and receiving and outputting measurement data measured by the measuring assembly; and a power module mounted on the combination portion of the base and providing electricity to the communication module and the multiple torque measuring apparatuses, and characterized in that: the combination portion has a first side fixed to the flywheel; and a second side opposite to the first side; the connection portion is attached to the first side of the combination portion; the communication module is mounted on the second side of the combination portion without being shielded by the flywheel; and the power module is mounted on the second side of the combination portion without being shielded by the flywheel. the combination portion has a first side fixed to the flywheel; and a second side opposite to the first side; the connection portion is attached to the first side of the combination portion; the communication module is mounted on the second side of the combination portion without being shielded by the flywheel; and the power module is mounted on the second side of the combination portion without being shielded by the flywheel.