Provided is a transmitter identifying apparatus configured to receive signals from terminals, extract a feature from the received signal, learn a first feature of the signal that is known as a signal received from a terminal to be discriminated, generate a first classifier for discriminating the terminal to be discriminated, input to the first classifier a second feature of the signal that is unknown whether the signal is received from the terminal to be discriminated, calculate a likelihood distribution representing likelihood for each terminal, analyze the likelihood distribution, determine whether to apply a tentative label to the second feature, and apply the tentative label to the second feature, based on a result of the analysis.