Portable electronic device

A portable electronic device where a battery pack can be installed smoothly, and electrical connection between the battery pack anc a portable electronic device main body can be made reliably and whose production cost can be reduced. A portable electronic device comprises a coolision avoidance mechanism provided with substantially fan-shaped up/down portions, adequately shaped push-up portions and climbing portions. The up/down portions and push-up portions are provided on inner wall faces that are provided for forming a battery chamber on both sides in the loading (alpha) direction of a battery pack and in the vicinities of corner portions where the inner wall faces cross a butting wall face perpendicular to the inner wall faces and provided for forming the battery chamber, and are higher than connection termnials. The climbing portions are provided on both sides in a battery pack width direction on the reverse side of the battery pack, in such a way as to face the up/down portions and the push-up portions. The climbing portions are projected in a fan shape so as to move over the connection terminals in the battery chamber by that move up and down while sliding on the fan-shaped faces of the up/down portions and the push-up portions.