Disclosed are an apparatus and method for communicating data in an in-vehicle network. The method, performed by apparatuses for communicating data on a transmission side and a reception side, includes determining, by the apparatus on the transmission side, whether data collected from the in-vehicle network is changed; creating, by the apparatus on the transmission side, an authentication value based on the determination as to whether the data is changed, creating a message including the data and the authentication value and transmitting the message to the apparatus on the reception side; receiving, by the apparatus on the reception side, the message; creating, by the apparatus on the reception side, a verification value using data extracted from the message; and verifying, by the apparatus on the reception side, the integrity of the apparatus on the transmission side by comparing the authentication value extracted from the message with the verification value.