This paper presents a modified deblocking filter for depth video coding in the 3D video coding extension of High Efficiency Video Coding (3D-HEVC). The conventional 3D video coding extension of HEVC (3D-HEVC) employs a deblocking filter and sample adaptive offset (SAO) in the loop filter in which both tools are applied to color video coding only. Nevertheless, the deblocking filter can smooth out blocking artifacts existing in coded depth videos, resulting in improving the coding efficiency. In this paper, we modify the original deblocking filter of HEVC and apply it to depth video coding. The goal is to enhance the depth video coding efficiency. The modified filter is executed when a set of conditions regarding the boundary strength are satisfied. In addition, the impulse response is altered for more smoothing between block boundaries. Experiment results show 5.2 % BD-rate reduction in depth video coding in comparison to the conventional 3D-HEVC.