PURPOSE: To obtain a signal compounding device which is free from the insertion loss by providing the resonant transfer circuit at the input and output side each plus the switch circuit which is turned on and off by the control signal.

CONSTITUTION: Plural signals enter resonant transfer circuits 24∼26 of the input side via input terminals 21∼23, and these circuits functions as the band-pass type filters. The signals charge the output-side capacity elements of the filters. Then the frequency is set so as to satisfy the sampling theorem to the compound wave, and switching circuits 27∼29 are closed for γ-second with virtually every TS to transfer the charged electric charge to resonant transfer circuit 35 of the output side through compound point 34. This charge charges the input-side capacity element of the output-side filter, and the discharge is carried out slowly to the load from output terminal 36. The control pulses entering circuits 27∼29 make the switch conduct for γ∼ second with virtually every TS, and thus the control pulses have no overlap to each signal wave. In such way, a signal compounding device can be obtained with no insertion loss caused.