A security signal transmission method performed by a first communication node includes estimating a radio channel between the first communication node and a second communication node; classifying all subcarriers into a first subcarrier group for transmitting a data signal and a second subcarrier group for transmitting a jamming signal based on estimated channel information; generating data symbol(s) by allocating the data signal to subcarriers of the first subcarrier group; generating jamming symbol(s) by allocating the jamming signal to subcarriers of the second subcarrier group; generating a first control symbol to which a first control signal is mapped, the first control signal including a first reference value used to restore the data symbols at the second communication node; and transmitting the data symbol(s), the jamming symbol(s), and the first control symbol to the second communication node.