Provided are FTN-based OFDM transmission apparatus and method for efficient coexistence of broadband and sporadic traffics which may share radio resources with a Nyquist rate or more of efficiency by inserting the sporadic traffic into resources allocated to the broadband traffic in uplink transmission of a mobile communication system and use the band multiplexing even to a multi input multi output (MIMO) transmission apparatus. According to the present invention, it is possible to reduce quality deterioration according to actual offloading of subcarriers by removing some frequency components to remove a frequency domain allocated with some subcarriers among frequency components of the broadband traffic to selectively offload subcarriers having low contribution rate for the actual broadband transmission and to use the sporadic traffic in a grant-free access scheme by using bands used for the offloaded subcarriers in the sporadic traffic transmission.