The Maxwell-displacement-current measurement (MDC) and surface pressure of chiral and racemic phospholipid [alpha -phosphatidylcholine dipalmitoyl (DPPC)] monolayers at the air-water interface by monolayer compression were performed. It was found that some critical MDC peaks were generated with different amplitude and sign depending on the chirality of the phospholipids in the plateau region. This anomalous MDC generation is theoretically interpreted as the molecular twist-conformation transition induced by monolayer compression.