Electrical noises in MoS₂-based conducting channels have been extensively studied by measuring the current noises from MoS₂-based devices. However, it has been very difficult to directly map the sources of such electrical noises in the channels. Herein, we report a method to directly map localized noise sources and their activities in a monolayer MoS₂ with a nanoscale resolution. In this method, currents and noises were measured through a conducting atomic force microscopy probe which made a direct contact on the monolayer MoS₂. By analyzing the measured data, we could estimate sheet resistance and noise source activities in the grain structures of the MoS₂, revealing clear correlations between them. In addition, we measured the effect of lights on noise sources activities inside MoS₂. Our results provide a valuable insight about noise source activities in MoS₂ and can be utilized for various electrical noise researches.