An apparatus and method for precisely measuring various biological information of a user's body by using a single measuring apparatus enable precisely and effectively measuring biological information including body fat, pulse and a blood vessel aging degree. By measuring an infrared absorbance or infrared rays irradiated to a measurement target according to a modulation and tuning method and obtaining the information with reference to supplementary biological information obtained from a user, the plurality of biological information can be precisely measured at a low driving voltage through the modulation and tuning method by using a single infrared light source. Also, the measuring apparatus can be reduced in size by simplifying its construction and can be effectively integrated into various device.