The present invention relates to an integrated viterbi decoder with improved test function. The viterbi decoder recovers original symbol and data bits from convolutional binary symbol stream, reducing a noise and data loss originated from a channel fading. For enhancing the test function of the viterbi decoder, the viterbi decoder of the present invention stores predetermined test control signals in a test register. During a test, the test control signals are synchronized with a test clock apart from a frame synchronous signal of the viterbi decoder. The test time of the viterbi decoder, thus, is not restricted by the frame synchronous signal. As a result, the test time of the viterbi decoder can be reduced without addition of an external pin.