A data transmission circuit includes: a driving voltage generation unit configured to generate a driving voltage having a lower level than an external driving voltage; a switch unit configured to transmit the driving voltage when any one of a write enable signal and a read enable signal is enabled; and a data transmission unit configured to be driven by receiving the driving voltage, transmit a signal of a DQ pad as data in response to the write enable signal, and transmit the data to the DQ pad in response to the read enable signal.