An electronic device is provided. The electronic device includes a housing structure that includes a ceramic portion including a ceramic material, and a polymer portion formed on an inner surface of the ceramic portion and including a polymer material, and an antenna structure that is disposed within the housing structure and radiates a radio frequency (RF) signal to an outside of the housing structure. The housing structure includes a first portion including at least a portion of a region through which the RF signal passes, and a second portion formed around the first portion. In the first portion, a ratio of a thickness of the polymer portion to an entire thickness of the first portion is a first ratio. In the second portion, a ratio of a thickness of the polymer portion to an entire thickness of the second portion is a second ratio.