An object of the invention is to smoothen the loading of a battery pack, to ensure the electric connection between the battery pack and the main body of a mobile electronic apparatus, and to reduce the manufacture cost. In the invention, a mobile electronic apparatus comprises collision avoiding mechanisms (4) including: generally sector-shaped ascent/descent portions (41A) and suitably shaped push-up portions (41B) disposed higher than and corresponding to connecting terminals (22) disposed in the battery chamber (22), on inner wall faces (21A/21B) formed on the two sides along the loading (.alpha.) direction of the battery pack (3) so as to form the battery chamber (21) and near the corner portions intersecting abutting wall faces (21C) perpendicular to the inner wall faces (21A/21B) for forming the battery chamber (21); and riding portions (42) formed on the back face of the battery pack (3) confronting the ascent/descent portions (41A) and the push-up portions (41B) on the two widthwise sides of the battery pack (3) and ascending/descending while sliding on the sector-shaped faces of the push-up portions (41B) thereby to ride over the connecting terminals (22) disposed in the battery chamber (21). When the battery pack (3) is loaded into the battery chamber (21), its riding portions (42) can ride on the ascent/descent portions (41) so that they can safely ride over the connecting terminals (22).