[en] The crystal structure and strain in a (100)/(001)-oriented PZT micro cantilever under applied voltage were characterized by in-situ Raman spectroscopy. A Pt/LaNiO₃/(100)/(001)PZT/LaNiO₃/Pt/Ti/SiO₂/silicon-on-insulator (SOI) multilayer structure was fabricated in a process based on a microelectromechanical system (MEMS). The volume fraction of the domain switching from a-domains to c-domains was monotonously increased with increases in the applied voltage. No compressive in-plane lattice strain was induced in the PZT film with the increases in the applied voltage. These results show that Raman spectroscopy is a useful method for in-situ observation of PZT micro cantilevers. (author)