Blue-painted pottery was produced in the New Kingdom, Egypt, and decorated with blue, red, and black pigment. In this study, two newly developed portable instruments, a portable X-ray fluorescence spectrometer and a portable X-ray powder diffractometer, were brought to the site on the outcrop at Northwest Saqqara, an archaeological site in Egypt, to verify their performance in on-site analysis of excavated artifacts at the site. Pigments used for the blue-painted pottery and plasters in the New Kingdom were analyzed by these instruments on the basis of both their chemical compositions and crystal-structural information. The blue pigments were identified as two different pigments, Egyptian blue and cobalt blue. The diffraction pattern of the blue pigment of the painted pottery exhibited that of spinel structure. The XRF spectrum of the blue pigment obtained by the same instrument from the same position indicates the presence of Mn, Co, Fe, Ni, and Zn. The possibility of compositional transitions of the cobalt blue pigment with time was revealed on by detailed analysis of the XRF data. The reason for the transitions is considered together with the archaeological background of the New Kingdom, Egypt.