Device for encoding a DPCM image is provided. A smoothness test is performed on an original image at a smoothness tester. A linearly predicted value of the original image is obtained at a linear predictor. A switching part operates depending on a result of the smoothness test. A difference between the linearly predicted value and the original image is quantized, and encoded when the result of the smoothness test is satisfactory. A difference between the linearly predicted value corrected by using space self-likeness of the image and the original image is quantized, and encoded when the result of the smoothness test is not satisfactory. The adaptive application of the existing linear prediction, and the prediction corrected by using self-likeness of space likeness of the image permits to obtain a better predicted value for DPCM, and improve an image compression efficiency.