A fundamental challenge to understanding effects of foreign language anxiety on the foreign language learning lies in implementing reliable and valid measures. Considering importance of measurement bias and widespread usage of the foreign language classroom anxiety scale (FLCAS) in education, the aim of the current study was to detect differential item functioning (DIF) in FLCAS due to male and female students, which threatens the validity of FLCAS. Results showed that gender related DIF appeared in FLCAS. Out of 25 items of FLCAS, two items were found to exhibit gender related DIF after correcting inflated Type I error. Such results implied that what previous studies called gender differences in the mean levels of foreign language classroom anxiety might have just been response differences to FLCAS due to some of gender related DIFs on FLCAS.