1. An image processing device comprising: a body hair detection unit that detects a body hair region corresponding to body hair from a process target image that includes skin; a texture structure estimation unit that estimates a structure of skin texture in the process target image; and an interpolation unit that interpolates the body hair region detected by the body hair detection unit based on the structure of the skin texture estimated by the texture structure estimation unit, wherein the texture structure estimation unit decides a second threshold value for distinguishing a skin ridge pixel from a skin groove pixel, determines whether a skin pixel is a skin ridge pixel or a skin groove pixel in a determination region with a pixel of interest in the body hair region regarded as a reference using the second threshold value, and estimates whether the pixel of interest is a skin ridge pixel or a skin groove pixel according to a proportion of the skin ridge pixel to the skin groove pixel within the determination region.