A building can be known by look shape, color, and texture. The building can be detected by using many methods and can be count population density in the area. Region growing is one simple segmentation method because only use seed point. Before segmentation, the image through preprocessing step include sharpening, binarization by the Otsu’s method. Sharpening for clarifying image and otsu method changed image valued 0 and 1. Next step is post-processing include segmentation using region growing and opening-closing operation. The last process is detection building where a building of detection will be signed. In this research, we present region growing for building segmentation by using both area and perimeter as an important variable in the region growing. The value of area more than 10 and perimeter is more than 50 are produced most of the building.