Mass spectrometry is a technique to ionize molecules and detect the mass-to-charge ratio of the generated ions. The technique is widely used in hospitals for pathogenic bacteria identification, as well as in environmental science and food science for biosafety control. This book summarizes the most recent development of mass spectrometry techniques in microbial analysis, including mass spectrometry-based microbial identification, bacterial antimicrobial resistance study, data mining algorithm development, omics for microbial research, applications in clinical diagnosis, environmental science and food science, and more. It will guide researchers in the field, and those who are about to enter the field, in the most appropriate methods to characterize microbes and enable their detection.