We propose a method for non-photorealistic color halftoning by an inverse box filter, that restores box blur in an iterative manner. The inverse box filter is a kind of sharpening filter, the characteristic of which is applicable to non-photorealistic halftoning. Experimental results show that the proposed method generates non-photorealistic halftone patterns on output images, where different patterns and sizes of the filter kernel bring different halftone patterns. Additionally, we present a memory-efficient method for implementing the inverse box filter, and demonstrate that the method is more effective than the original one.