To provide a structure to dissipate heat from an internal heating component efficiently for a miniaturized, thin portable electronic apparatus. The portable electronic apparatus comprises a housing 1, a circuit board 7 accommodated in the housing and mounted with an electronic component on a surface on one side of the circuit board, a thermally conductive member 6 arranged opposite to the surface on one side of the circuit board and having thermal conductive property, and a battery accommodated in a battery chamber 8 formed in the housing. The thermally conductive member 6 forms at least a part of the battery chamber 8.