An object of the present invention is to provide an antenna structure having high reception performance and having neither material limitations nor design limitations, and to provide a radio controlled wristwatch utilizing the antenna structure as mentioned above, and further wherein the present invention relates to an antenna structure to be used inside a metal outer casing and having a configuration which receives radio wave, the antenna structure being characterized by having a structure wherein a coil is wound about a magnetic core and being able to receive a magnetic flux from outside the metal outer casing.