Abstract: The present invention provides an attachable pocket for stretchable pants comprising: a container defining an interior volume by a front wall and a back wall and having an opening; an electromagnetic fields (EMF) protection member attached to the back wall, and an attachable member attached to the back wall. Also, the present invention provides a garment with stretchable pants and a detachable pocket, the garment comprising: stretchable pants having a different shape according to a wearer; and a detachable pocket made of non-stretchable material and providing defined interior volume, the detachable pocket comprising: a container comprising of a front wall and a back wall; an electromagnetic fields (EMF) protection member attached to the back wall, and an attachable member attached to the back wall.