An apparatus for estimating bio-information based on pulse wave signals of multiple wavelengths is disclosed. The bio-information estimating apparatus may include: a sensor part comprising a pulse wave sensor configured to measure a multi-wavelength pulse wave signal at a first point in time when a first pressure is applied from an object to the sensor part and at a second point in time when a second pressure is applied from the object to the sensor part; and a processor configured to estimate bio-information based on a difference between the multi-wavelength pulse wave signal measured at the first pressure and the multi-wavelength pulse wave signal measured at the second pressure.