Provided are a method and apparatus for measuring an isoelectric point using a field effect transistor. The method includes providing a field effect transistor including a substrate, source and drain electrodes disposed on the substrate and spaced apart from each other, and a channel region between the source and drain electrodes, providing a first electrolyte solution having a first concentration to the channel region of the field effect transistor and measuring a first current value of the channel region between the source and drain electrodes, providing a second electrolyte solution having a second concentration greater than the first concentration and measuring a second current value of the channel region between the source and drain electrodes, and determining as the isoelectric point of the field effect transistor or a material disposed on the field effect transistor using a difference between the first and second current values.