A bio-information measuring apparatus (900; 1300) comprising: a pulse wave sensor (910; 1311a) configured to measure a plurality of pulse wave signals having different wavelengths from an object, wherein the pulse wave sensor comprises: a first pulse wave sensor comprising a first light source configured to emit a light of a first wavelength onto the object, and a first detector configured to measure a first pulse wave signal in response to the light of the first wavelength returning from the object; and a second pulse wave sensor comprising a second light source configured to emit a light of a second wavelength, which is different from the first wavelength, onto the object, and a second detector configured to measure a second pulse wave signal in response to the light of the second wavelength returning from the object; a contact pressure (930; 1311b) sensor configured to measure a contact pressure of the object while the plurality of pulse wave signals are measured; and a processor (920; 1312) configured to obtain an oscillometric waveform based on the contact pressure and a difference signal obtained from the first pulse wave signal and the second pulse wave signal from the plurality of pulse wave signals having the different wavelengths, and obtain bio-information based on the oscillometric waveform, wherein the first wavelength is longer than the second wavelength, and wherein the difference signal is obtained by subtracting a differential signal of the second pulse wave signal from a differential signal of the first pulse wave signal. a pulse wave sensor (910; 1311a) configured to measure a plurality of pulse wave signals having different wavelengths from an object, wherein the pulse wave sensor comprises: a first pulse wave sensor comprising a first light source configured to emit a light of a first wavelength onto the object, and a first detector configured to measure a first pulse wave signal in response to the light of the first wavelength returning from the object; and a second pulse wave sensor comprising a second light source configured to emit a light of a second wavelength, which is different from the first wavelength, onto the object, and a second detector configured to measure a second pulse wave signal in response to the light of the second wavelength returning from the object; a first pulse wave sensor comprising a first light source configured to emit a light of a first wavelength onto the object, and a first detector configured to measure a first pulse wave signal in response to the light of the first wavelength returning from the object; and a second pulse wave sensor comprising a second light source configured to emit a light of a second wavelength, which is different from the first wavelength, onto the object, and a second detector configured to measure a second pulse wave signal in response to the light of the second wavelength returning from the object; a contact pressure (930; 1311b) sensor configured to measure a contact pressure of the object while the plurality of pulse wave signals are measured; and a processor (920; 1312) configured to obtain an oscillometric waveform based on the contact pressure and a difference signal obtained from the first pulse wave signal and the second pulse wave signal from the plurality of pulse wave signals having the different wavelengths, and obtain bio-information based on the oscillometric waveform, wherein the first wavelength is longer than the second wavelength, and wherein the difference signal is obtained by subtracting a differential signal of the second pulse wave signal from a differential signal of the first pulse wave signal.