IDDQ testing strongly requires to reduce the number of times of IDDQ measurements, because IDDQ measurement is time-consuming. Therefore it is important to select small number of IDDQ measurement vectors in a test sequence for a sequential circuit while fault coverage is nearly maximum. In this paper, we give a new selection problem of measurement vectors by introducing a cost function which is defined by the number of measurement vectors and fault coverage. The proposed method for selecting measurement vectors optimizes the cost function so that high fault coverage would be obtained by a small number of measurement vectors.