A detecting apparatus and a detecting method for physiological information are provided. The detecting apparatus includes a first optical signal provider configured to provide an organism with a first optical signal, a signal receiver configured to receive the first physiological signal, and a processor. The first optical signal, after interacting with the organism, turns into a first physiological signal. The processor is configured to calculate a plurality of physiological information values of the organism according to the first physiological signal; determine whether or not any of the physiological information values is abnormal; and replace the abnormal physiological information value with a physiological information reliable value when there is the abnormal physiological information value.