A motion artifact detecting method using wavelet transform which is capable of removing the problem caused by a radio noise and a motion artifact generated during the measurement of a PPG signal which is one of bio-signals, the method including: measuring a PPG signal generating a signal obtained by removing a radio noise from the measured PPG signal setting a reference signal from the signal from which the radio noise is removed selecting a base signal based on the set reference signal performing wavelet transform using the base signal and detecting and removing a motion artifact using the wavelet-transformed value.