This book presents a large amount of Heat Shock Factor-related information, describes core observations about molecular mechanisms and pathophysiological roles, and provides concepts on the basis of information from diverse aspects. This adaptive response to high temperature or protein misfolding is a fundamental mechanism to maintain capacity of protein homeostasis or proteostasis, and evolutionally conserved among all living organisms, including bacteria and human, on the earth. Furthermore, physiological and pathological roles of Heat Shock Factor (HSF) have been extensively studied in fruit fly, worm, and mouse models. It has been revealed that HSF play roles in development of the brain, reproductive and sensory organs, and in ageing, inflammation, and circadian rhythm. Analysis of the mechanisms have uncovered that HSF exerts a wide range of effects on gene expression and epigenetic status on whole genome. Moreover, loss or gain of HSF function is also tightly related with protein-misfolding diseases including neurodegenerative diseases, psychiatric diseases, heart diseases, and cancers. Therefore, HSF is now thought to be a promising therapeutic target for treatment of these refractory diseases.For undergraduate students, this is a higly understable texbook of heart shock response and HSF, covering basis of HSF biology, physiological role of HSF and disease associated with HSF function. This book will not only be a guide of the heat shock response and HSF for students and young researchers in other fields, but also be a cornerstone for future works in the field related with the heat shock response and HSF.