Imaging of biological membranes is a useful method for visualizing and spatiotemporal analysis of membrane morphology and dynamics in living cells. Fluorescent membrane probes are powerful imaging tools for specifically labeling biological membranes (Fig. 24.1). So far, lipophilic fluorescent dyes [1] and lipid-dye conjugates [2] have been developed. Furthermore, environment-sensitive dyes visualize the differences in the physical properties of membranes such as fluidity and tension by changes in the fluorescence intensity or wavelength [1, 3]. In addition to plasma membranes, fluorescent probes that can selectively label organelle membranes have also been developed in recent years, and differences in the physical properties of each organelle membrane are being discussed [3]. Furthermore, there has been significant progress on fluorescence microscope, such as fluorescence lifetime imaging microscopy for quantitative analysis of dynamic changes in membrane environment [4] and super-resolution microscopy for visualization of detailed organelle structures and their interactions [5].