A system and method for measuring concentration of a constituent of a specimen are provided. The system includes an oscillator for outputting, towards the specimen, electromagnetic waves having respective different frequencies between 5 GHz and 300 GHz; a detector for detecting the electromagnetic waves that are reflected from the specimen; and a processor measuring at least one of reflection coefficient and complex permittivity of the electromagnetic waves detected and calculating the concentration of the constituent of the specimen based upon at least one of the reflection coefficient measured and the complex permittivity measured.