An apparatus for transforming an image in a mobile device is disclosed. The apparatus comprises a pen style transformation unit for transforming an original image to a pen style image using a separated Gaussian filter and outputting pen style image, a cartoon style transformation unit for transforming the original image to a cartoon style image and outputting the cartoon style image, a mosaic creation unit for creating a photomosaic to which the original image is applied based on an optimum photo image set and outputting the created photo mosaic by applying the created photo mosaic to the original image, and an image output unit for outputting the images output from the pen style transformation unit, the cartoon style transformation unit, and the mosaic creation unit to an output unit.