A PCM signal recording/reproducing apparatus includes write means for writing data on a recording medium, a data detecting circuit for detecting data from the recording medium, a temporary storage unit for storing temporarily the data to be recorded on the recording medium or the data reproduced from the recording medium, an error correcting circuit for correcting error of the data through cooperation with the storage unit and a switching circuit for changing over a first mode in which first data of two channels each having a sampling frequency of 48 KHz and a quantization bit number of n are recorded/reproduced with a second mode in which second data of two channels each having a sampling frequency of 32 KHz and a quantization bit number of n are recorded/reproduced in accordance with a recording format having a data location for the input data and dummy data location for dummy data to be added to the input data. Upon recording/reproduction of data of four channels including data of main two channels each having a sampling frequency of 32 KHz and a quantization number bits of n and two-sub-channels, recording/reproduction mode is changed over to the second mode in which the main two channel data are disposed at a data location on the recording format through the storage unit, while the input sub-two-channel data are disposed at the location for the dummy data on the recording format through a second block address control circuit.