Passive Acoustic Mapping (PAM) is a method for monitoring cavitation induced by high-intensity focused ultrasound. In this paper, we present a portable imaging system capable of monitoring the intensity map of cavitation in real time. For implementing frequency domain PAM in a FPGA, it is designed to use as few resources as possible in the calculation process. The probe system performs PAM and B-mode imaging, and images are shown in the PC GUI. As a result, the accuracy and stability of the system have been verified through experiments with a HIFU transducer and a linear array transducer.