An apparatus for estimating bio-information, the apparatus comprising: a sensor configured to obtain a bio-signal from an object using PPG, photoplethysmography; and a processor configured to: obtain a second-order differential signal of the bio-signal; determine whether a first local minimum point of the second-order differential signal is stable by determining whether there is no inflection point in a detection period of the second-order differential signal; and extract a progressive wave component from the bio-signal, wherein, when the first local minimum point of the second-order differential signal is determined to be stable, the progressive wave component is extracted from the bio-signal by extracting, as the progressive wave component, at least one of an amplitude of the bio-signal, which corresponds to a time of the first local minimum point of the second-order differential signal, and an amplitude of the bio-signal which corresponds to an internally dividing point between the time of the first local minimum point and a time of a second local maximum point of the second-order differential signal, and wherein, when the first local minimum point of the second-order differential signal is determined to be unstable, the progressive wave component is extracted from the bio-signal by extracting a maximum amplitude point in a systolic portion of the bio-signal and extracting, as the progressive wave component, at least one of an amplitude of the maximum amplitude point, and an amplitude of the bio-signal which corresponds to an internally dividing point between a time of the inflection point, which is detected in the detection period of the second-order differential signal, and a time of the maximum amplitude point. a sensor configured to obtain a bio-signal from an object using PPG, photoplethysmography; and a processor configured to: obtain a second-order differential signal of the bio-signal; determine whether a first local minimum point of the second-order differential signal is stable by determining whether there is no inflection point in a detection period of the second-order differential signal; and extract a progressive wave component from the bio-signal, wherein, when the first local minimum point of the second-order differential signal is determined to be stable, the progressive wave component is extracted from the bio-signal by extracting, as the progressive wave component, at least one of an amplitude of the bio-signal, which corresponds to a time of the first local minimum point of the second-order differential signal, and an amplitude of the bio-signal which corresponds to an internally dividing point between the time of the first local minimum point and a time of a second local maximum point of the second-order differential signal, and wherein, when the first local minimum point of the second-order differential signal is determined to be unstable, the progressive wave component is extracted from the bio-signal by extracting a maximum amplitude point in a systolic portion of the bio-signal and extracting, as the progressive wave component, at least one of an amplitude of the maximum amplitude point, and an amplitude of the bio-signal which corresponds to an internally dividing point between a time of the inflection point, which is detected in the detection period of the second-order differential signal, and a time of the maximum amplitude point. obtain a second-order differential signal of the bio-signal; determine whether a first local minimum point of the second-order differential signal is stable by determining whether there is no inflection point in a detection period of the second-order differential signal; and extract a progressive wave component from the bio-signal, wherein, when the first local minimum point of the second-order differential signal is determined to be stable, the progressive wave component is extracted from the bio-signal by extracting, as the progressive wave component, at least one of an amplitude of the bio-signal, which corresponds to a time of the first local minimum point of the second-order differential signal, and an amplitude of the bio-signal which corresponds to an internally dividing point between the time of the first local minimum point and a time of a second local maximum point of the second-order differential signal, and wherein, when the first local minimum point of the second-order differential signal is determined to be unstable, the progressive wave component is extracted from the bio-signal by extracting a maximum amplitude point in a systolic portion of the bio-signal and extracting, as the progressive wave component, at least one of an amplitude of the maximum amplitude point, and an amplitude of the bio-signal which corresponds to an internally dividing point between a time of the inflection point, which is detected in the detection period of the second-order differential signal, and a time of the maximum amplitude point.