A wrist mountable electronic device case such as a wrist watch case includes: a main body of a synthetic resin, in and on which a housing portion and a pair of band attaching portions are formed, one attaching portion being formed with an antenna containing area; a metallic sheath member mounted on a top surface of the body, having an opening corresponding to a top opening of the housing portion, and not covering the containing area; a light transmitting member mounted on the opening of the sheath member; a metallic back cover covering a bottom opening of the housing portion; and a fixing unit fixing the sheath member and the back cover with each other while sandwiching the main body therebetween. A watch module is housed in the housing portion, an antenna is contained in the containing area, and a lead connects the antenna to the watch module.