Inducers are critical to the minimization of the degradation of a liquid oxygen (LOX) pump and the maximization of the thrust-to-weight ratio of liquid rocket engines, but create cavitation instabilities that have adverse effects on its reliabilities. To examine the cavitation instabilities of an inducer in a LOX pump, two kinds of working fluids, water and liquid oxygen, were employed. The cavitation instabilities were measured with an accelerometer installed on the pump casing, instead of pressure pulsation sensors, which are complicated to install. The flow coefficient and the head slightly decrease with decreases in the cavitation number before the cavitation breakdown. Several cavitation instabilities were clearly identified with the accelerometer regardless the fluids. Especially the super-synchronous rotating cavitation and asymmetric cavitation are dominant in accelerometer signals, which had radial impacts on the rotordynamcis. The features of the instabilities are well-matched with the previous studies and the pressure pulsation sensor data. In addition, the fluids effects were explored. When flow coefficients were 0.09 and 0.10, super-synchronous rotating cavitation was found in a similar cavitation number range for both fluids. Whereas, when the flow coefficient was 0.11, the cavitation numbers of the cavitation instabilities in the liquid oxygen test are smaller than those of the water test.