Provided is a microanalysis method and system using a Field Effect Transistor (FET). The microanalysis method includes a channel region having a receptor molecule fixed; forming a nano-particle conjugate in the channel region by supplying a sample for test and the nano-particle conjugate to the FET; growing a probe material on the channel region; and measuring a current flowing through the channel region, wherein the receptor molecule is a material that is selectively bonded to a target molecule in the sample for test.