We study DOT using 2-dimensional continuous-wave source-detector arrays on the surface of semi-infinite medium, aiming at imaging the perfusion and the hemoglobin oxygen saturation variation of the human cerebral cortex with the brain activation. We had been formulating the inverse problem with the Moore-Penrose inversion. When we use simple regularization in the inverse problem, the reconstruction sensitivity decreases markedly with the depth so that the signal in the deep range may be masked by the unwanted signal in the shallow range. In this report, we propose a reconstruction of a depth-adaptive regularization scheme, in which we assign the smaller regularization parameter with the depth. We demonstrate the improvement of the 3-dimensional reconstruction uniformity using proposed scheme.