Capability of diagnostic imaging of an early stage breast tumor using microwaves has been investigated by means of FDTD-based numerical simulations. More than ten years ago, we developed chirp pulse microwave computed tomography (CP-MCT) for microwave imaging of a human body. In this study, we'll show that CP-MCT provides useful information on the tumor region in the breast. To specify the exact location of an early stage tumor inside the breast, image restoration has been attempted by computing the point spread function (PSF) of CP-MCT in two- or three-dimensional ways by assuming the function is linear. Another solution is given by using radar imaging system simultaneously with CP-MCT.