Abstract: Provided are microwave image reconstruction apparatus and method. An apparatus for diagnosing a breast cancer, includes: a plurality of antennas for inserting a breast and configured to transmit and receive the electromagnetic wave; an electromagnetic wave transceiver configured to receive phase and amplitude information of the electromagnetic wave; an initial distribution value provider configured to set an initial dielectric constant and conductivity distribution value for dielectric constant and conductivity of a breast of a patient and in the tank; a first image reconstruction unit configured to transform the amplitude information of the electromagnetic wave through log transform and to obtain a first image by calculating a phase and amplitude information value of electric field generated from the electromagnetic wave; and a second image reconstruction unit configured to transform the first image in a value in a complex number form and to transform values to a second image.