A wafer for backside illumination type solid imaging device having a plurality of pixels inclusive of a photoelectric conversion device and a charge transfer transistor at its front surface side and a light receiving surface at its back surface side is produced by a method comprising a step of forming a BOX oxide layer on at least one of a wafer for support substrate and a wafer for active layer, a step of bonding the wafer for support substrate and the wafer for active layer and a step of thinning the wafer for active layer, which further comprises a step of forming a plurality of concave portions on a bonding face of the BOX oxide layer to the other wafer and filling a polysilicon plug into each of the concave portions to form a composite layer before the step of bonding the wafer for support substrate and the wafer for active layer.