We observed the phase behaviors, and the changes of membrane fluidity in lipid membranes containing local anesthetics (LAs), lidocaine and tetracaine. The phase separation in DOPC/DPPC binary membranes had not been changed significantly by addition of LAs, whereas that in DOPC/DPPC/Chol ternary membranes was suppressed by LAs. In order to evaluate the membrane fluidity, Laurdan generalized polarization values of membranes were measured. The fluidity of DOPC-rich phase in the ternary membrane became lower as LAs concentration had increased. Our results indicated the correlation between physical property change on membrane and pharmacological functions of LAs.