A dimension measurement system is provided. The dimension measurement system includes a speech I/O device fit in an ear canal of a worker, generating a voice signal from vibration in the air emitted from an eardrum of the worker and propagated inside the ear canal, and outputting the voice signal and an information processing device realizing a speech recognition function recognizing a measurement value of a dimension of an object from the voice signal that the speech I/O device output and a judgment function judging if the measurement value satisfies a reference value of the object.