For decoding by the use of a decoder buffer memory (14) an encoded video signal into which an encoder input signal is encoded with data compression on a basis of frames, a decoding device comprises a control signal producing unit (16) for delivering a decoder control signal to a decoder (15) when the frame of data written into the buffer memory coincides with the frame of data read out of the buffer memory. Responsive to the control signal, the decoder produces a supply control signal to the buffer memory to stop delivery of the read-out data to the decoder. Preferably, the decoding device should comprise a processing unit (11) for producing frame pulses at heads of the respective frames of the encoded video signal. A counter (12) counts the frame head pulses to make the write-in data and the read-out data indicate frame numbers for use in the signal producing unit. Alternatively, the decoding device may receive an encoded video signal in which frame number data are included for use in the signal producing unit.