Provided is an oxygen sensor using surface plasmon resonance, including: a laser diode emitting light; a polarizer converting the emitted light into polarized light; a prism receiving the polarized light from the polarizer and having a sensor substrate on one surface thereof so that the polarized light is reflected, the sensor substrate coated with oxygen-sensitive organic material; an oxygen concentration measurement chamber provided to enclose the sensor substrate so that oxygen whose concentration is to be measured is contained therein; a photodiode measuring an amount of light reflected from the prism; and a microcontroller unit controlling operation of the oxygen sensor and calculating the oxygen concentration. Further, the oxygen concentration is determined using the microcontroller unit having absolute concentrations corresponding to the amount of light measured using the photodiode, and the oxygen concentration is measured where an incidence angle of the polarized light incident on the sensor substrate is fixed.