An apparatus for estimating bio-information, the apparatus comprising: a first sensor configured to measure a first pulse wave signal of an infrared wavelength and a second pulse wave signal of a green wavelength from an object; a second sensor configured to measure at least one of a force or a pressure applied to the object; and a processor configured to: generate an oscillometric waveform envelope based on the first pulse wave signal of the infrared wavelength and the at least one of the force or the pressure applied to the object, and detect a characteristic point from the oscillometric waveform envelope; obtain a feature value from the detected characteristic point of the oscillometric waveform envelope, wherein the feature value comprises at least one of a force value, a pressure value, and an amplitude value of the characteristic point; extract a direct current, DC, component of the second pulse wave signal of the green wavelength, and predict a size of a measured blood vessel based on the DC component value corresponding to the force value or the pressure value of the characteristic point; correct the feature value based on the size of the measured blood vessel; and estimate the bio-information based on correcting the feature value, wherein the processor is further configured to: normalize the DC component of the second pulse wave signal of the green wavelength; in response to a normalized DC component value, corresponding to the force value or the pressure value of the characteristic point, being less than a reference value, predict that the size of the measured blood vessel is less than a size of a target blood vessel; and in response to the normalized DC component value exceeding the reference value, predict that the size of the measured blood vessel is greater than the size of the target blood vessel. a first sensor configured to measure a first pulse wave signal of an infrared wavelength and a second pulse wave signal of a green wavelength from an object; a second sensor configured to measure at least one of a force or a pressure applied to the object; and a processor configured to: generate an oscillometric waveform envelope based on the first pulse wave signal of the infrared wavelength and the at least one of the force or the pressure applied to the object, and detect a characteristic point from the oscillometric waveform envelope; obtain a feature value from the detected characteristic point of the oscillometric waveform envelope, wherein the feature value comprises at least one of a force value, a pressure value, and an amplitude value of the characteristic point; extract a direct current, DC, component of the second pulse wave signal of the green wavelength, and predict a size of a measured blood vessel based on the DC component value corresponding to the force value or the pressure value of the characteristic point; correct the feature value based on the size of the measured blood vessel; and estimate the bio-information based on correcting the feature value, wherein the processor is further configured to: normalize the DC component of the second pulse wave signal of the green wavelength; in response to a normalized DC component value, corresponding to the force value or the pressure value of the characteristic point, being less than a reference value, predict that the size of the measured blood vessel is less than a size of a target blood vessel; and in response to the normalized DC component value exceeding the reference value, predict that the size of the measured blood vessel is greater than the size of the target blood vessel. generate an oscillometric waveform envelope based on the first pulse wave signal of the infrared wavelength and the at least one of the force or the pressure applied to the object, and detect a characteristic point from the oscillometric waveform envelope; obtain a feature value from the detected characteristic point of the oscillometric waveform envelope, wherein the feature value comprises at least one of a force value, a pressure value, and an amplitude value of the characteristic point; extract a direct current, DC, component of the second pulse wave signal of the green wavelength, and predict a size of a measured blood vessel based on the DC component value corresponding to the force value or the pressure value of the characteristic point; correct the feature value based on the size of the measured blood vessel; and estimate the bio-information based on correcting the feature value, wherein the processor is further configured to: normalize the DC component of the second pulse wave signal of the green wavelength; in response to a normalized DC component value, corresponding to the force value or the pressure value of the characteristic point, being less than a reference value, predict that the size of the measured blood vessel is less than a size of a target blood vessel; and in response to the normalized DC component value exceeding the reference value, predict that the size of the measured blood vessel is greater than the size of the target blood vessel. normalize the DC component of the second pulse wave signal of the green wavelength; in response to a normalized DC component value, corresponding to the force value or the pressure value of the characteristic point, being less than a reference value, predict that the size of the measured blood vessel is less than a size of a target blood vessel; and in response to the normalized DC component value exceeding the reference value, predict that the size of the measured blood vessel is greater than the size of the target blood vessel.