A protective structure and an electronic device using the same are disclosed. The electronic device includes a first housing member, a second housing member, a blocking unit, and an operating module. The second housing member faces the first housing member, wherein a slit is located at the periphery of an enclosure disposed between the first and second housing members. The blocking unit, having a shape compatible with the shape of the slit, is disposed therein and includes a sealing member and a first foamable material. The sealing member is compressed by the first and second housing members, and the first foamable material is formed in the slit along an extending direction of the sealing member.