A signal transponder transceiving signals using different communication protocols has a control module, a receiving module and a transmitting module. The control module is electrically connected to the receiving module and the transmitting module, is built in with multiple communication protocols, decodes a tire pressure signal transmitted from and encoded by an external tire pressure sensor with one of the communication protocols, encodes the decoded information to a new tire pressure signal, and further transmits the new tire pressure signal to a tire pressure receiver. Accordingly, there is no failure in decoding and transmissions and cost increase when the signal transponder communicates with tire pressure sensors and a tire pressure receiver using two different communication protocols.