In scanning tomographic acoustic microscopy (STAM), projection error correction is necessary for high-resolution tomographic reconstruction. In this paper, both phase and alignment errors are examined. These errors arise from several sources, including the quadrature receiver channels, the unknown initial phase term, and any misalignment in the rotational scan. The data acquisition process and the image formation algorithm for the STAM are reviewed, and a description of error estimation and correction is also presented. Experimental results from the STAM are included to demonstrate the capability and effectiveness of the error-removal techniques.