In an access controller provided for a musical sound signal generating system, a signal generating section operates when a readout of wave data of one block stored in a working memory is completed in a sound channel, for supplying a next waveform request signal to a CPU, which requests a next block of the wave data for the sound channel. First and second buffer memories are connected between a recording medium and the working memory respectively through first and second buses which are independent from each other. A first transmitting section operates when receiving block specifying information from the CPU, which specifies a block to be read next from the recording medium, for transmitting the wave data of the specified block to either of the first or second buffer memory while reading the specified block of the wave data from the recording medium. A second transmitting section operates when the transmitting of the wave data to either of the first or second buffer memory is finished and during a period when the musical sound signal generation system is not accessing the working memory, for transmitting the wave data of the specified block to the working memory from either of the first or second buffer memory, to which the wave data of the specified block has been transmitted by the first transmitting section.