PURPOSE: To provide a simultaneous transmission reception communication method and to realize a method as the simultaneous transmission reception communication equipment at a low cost in which the increase in a speech frequency band due to time axis compression of a voice signal is not caused and the deterioration in voice quality is sufficiently suppressed.

CONSTITUTION: A voice signal is multiplexed by superimposing an original spectrum signal (a) obtained through a comb-line filter 11 and an inverted spectrum signal (b) obtained by inverting the frequency arrangement of the signal (a) at a spectrum inversion circuit 13 with each other thereby interpolating missing of a reception signal for a transmission period. The comb-line filter 11 acts as forming alternately its pass band and its block band at a predetermined frequency interval Δf and like forming a frequency space between the pass bands. Then the signals are superimposed by utilizing the space period to implement the simultaneous transmission reception communication through a single transmission system without causing the deterioration in sound quality.