This paper assumes a simple model for the DRAW (direct‐read/after‐write) optical disk using a Te‐alloy recording medium. The scattering of the light‐beam by the pit or boss of arbitrary shape on the boundary of three‐layered dielectrics is analyzed by the boundary‐element method. The sum and the differential signal output characteristics of the two‐split‐type optical detector also is discussed. The results of simulation are shown for the effect of the adjacent pit in the square and V‐shaped pregrooved models, the dependencies of the sum and the differential signals on the tracking error, and the dependencies of the sum and the differential signals on the pit depth, when the signal recording pit is provided in the two types of pregrooved models.