Аннотация:Broad-band UBVRJHKLM photometric data taken at the time of the optical maximum of the symbiotic binary Z And during its small-amplitude brightening in the end of 2002 are analyzed. The spectral energy distribution of each component of the binary has been obtained. The analysis shows that the energy distribution of the compact companion was changed very small, it was remained a hot object emitting mostly in UV as in the quiescent state of the system. On the basis of this result the brightening is supposed to be due to a slow expansion to about two times its quiescent size as a result of an accretion rate increase.