An apparatus for non-invasively measuring bio-information is provided. The apparatus for estimating bio-information may include a pulse wave sensor including a plurality of channels, and configured to measure pulse wave signals at a plurality of points of an object; and a processor configured to generate oscillograms corresponding to the plurality of channels based on the pulse wave signals measured by the plurality of channels; determine a channel, from among the plurality of channels, for estimating the bio-information based on the oscillograms; and estimate the bio-information based on an oscillogram of the channel.