An apparatus for measuring bio-information may include a pulse wave sensor that may measure a pulse wave signal from an object in contact with a measurement surface. The apparatus may include a force sensor that may measure a contact force between the pulse wave sensor and the object. The apparatus may include a fastener configured to fasten the pulse wave sensor to an electronic device such that the pulse wave sensor is rotatable around a center axis in a length direction of the pulse wave sensor. The apparatus may include a processor that may determine a direction in which a measurement region of the pulse wave signal or the measurement surface of the pulse wave sensor is oriented, select a measurement mode from among a plurality of measurement modes, and estimate bio-information of the object.