A recent advance in thermal imaging is overviewed with the actual imaging results using an infrared camera applied to the micro-scale heat transfer observation. The micro-scale visual thermal analysis and the lock-in thermography are presented. The latent heat's generation and dissipation at minus temperature during freezing of biological plant and animal cells are visualized that clarifies the thermal diffusion effect on crystallization and the vitrification. The onlamellae thermal analysis of n-alkane visualizes the early stage of anisotropic lamella formation. The crystallization front of polymeric spherulite of poly(ethylene oxide) visualizes the temperature rise of ~ 200 mK. The basic results of lock-in thermography visualizing the in-plane thermal diffusivity and the thermal interface are presented with a modulated spot heating method using a diode laser that is used to generate a thermal wave inside the specimen. A promising future of micro-bolometer sensor is introduced.