The present invention relates to an antenna structure in which an antenna pattern is formed on an inner surface of a case of a terminal device, and a method of manufacturing an antenna. In the present invention, an optimal antenna pattern is shaped in accordance with a frequency characteristic of a terminal device and the antenna pattern is directly printed on an inner surface of the terminal device through a vacuum evaporation or sputtering method. At this time, a mask member having the same shape as that of the antenna pattern is further provided. Alternatively, a transfer paper with the antenna pattern printed thereon may be attached to the inner surface of the terminal device. Therefore, even a complex antenna pattern can be easily implemented in the terminal device. Further, an optimal antenna characteristic can be obtained since the antenna is spaced apart from a printed circuit board by a predetermined distance.