A multimedia device including a back-end substrate that includes a heat source and a reproducing unit that is configured to reproduce an audio and/or a video signal based on data read from a storage medium, a housing that accommodates a back-end substrate and comprises an upper cover and a lower base which are respectively disposed above and under the back-end substrate, and a heat-dissipating structure that is formed on at least one of the upper cover and the lower base and contacts a side of the back-end substrate, a support post formed on the lower cover that is configured to support a lower surface of the back-end substrate, and a push post that is configured to position an upper edge of the back-end substrate with respect post the support post.