The invention relates to a method for making a transaction of a contactless application secure, said application (11) being stored in the mobile terminal (10), said transaction taking place between the mobile terminal and a contactless reader (12), said terminal including a security element (14), said method comprising the following steps carried out by the mobile terminal: the application sends (E13) a token representing a piece of sensitive data and a first authentication value relating to the token to the reader, the security element receives (E16) the token and the related first authentication value from the reader, the security element calculates (E17) a second authentication value from the received token and compares the first authentication value with the second authentication value, and sending (E18) the result of the comparison to the reader, said reader cancelling the transaction if the result is negative.