A digital indication type length measuring system includes a length measuring device having a spindle which can be brought into abutting contact with a work to be measured, an encoder for representing a displacement of the spindle as an electric signal, and an output circuit for outputting measured length information data obtained from the electric signal from the encoder to a cable. A data processing device includes an input circuit coupled to the cable for receiving data from the length measuring device, a processing circuit for processing data received by the input circuit in a predetermined manner to produce quality control data, and a printer for printing out the quality control data. The quality control data includes a histogram. When the length measuring and data processing devices are disconnected from each other, each measured length is displayed on a digital indicator which is provided on the length measuring device and which is repsonsive to the electric signal from the encoder.