Fuente: WIPO "tomato" Provided are: a pH-sensitive cationic lipid which can be more easily synthesized through a small number of steps without requiring any organometal reaction or use of any relatively expensive starting materials; and lipid nanoparticles including the lipid. Disclosed is a pH-sensitive cationic lipid comprising a compound represented by general formula (I) or (I'), wherein R1, Z2, s, Z1, and X are as defined in the description.