A battery pack comprising: a battery pack case having a substantially box-like shape whose upper surface is opened; a battery pack cover which closes the battery pack case; an air-suction portion with an air inlet; an air-exhaust portion with an air outlet; a junction box disposed in a junction box accommodating portion that is an interior space of the battery pack case between a pair of partition walls (5a, 5b) that are spaced from each other; the battery pack case being divided by the junction box accommodating portion into a first battery accommodating portion and a second battery accommodating portion (8a, 8b) that are located upstream and downstream of the junction box accommodating portion, respectively; and a plurality of battery modules accommodated in the first and second battery accommodating portions (7, 8a, 8b) of the battery pack case, wherein a first side air flow path for allowing air sucked through the air-suction portion to flow therethrough is formed between one of opposite sidewalls of the battery pack case and opposing battery modules, the first side air flow path being in communication, at its first region and second region (14, 15), with the first and second battery accommodating portions (7, 8a, 8b) of the battery pack case, respectively, the junction box accommodating portion is covered with a shield member (21, 22, 23, 23a, 23b), and the shield member is configured to prevent air that is supplied from the air-suction portion and flows along the first region of the first side air flow path from flowing into the junction box accommodating portion and guide air from the first region of the first side air flow path along the shield member to the second region (14, 15) of the first side air flow path. a battery pack case having a substantially box-like shape whose upper surface is opened; a battery pack cover which closes the battery pack case; an air-suction portion with an air inlet; an air-exhaust portion with an air outlet; a junction box disposed in a junction box accommodating portion that is an interior space of the battery pack case between a pair of partition walls (5a, 5b) that are spaced from each other; the battery pack case being divided by the junction box accommodating portion into a first battery accommodating portion and a second battery accommodating portion (8a, 8b) that are located upstream and downstream of the junction box accommodating portion, respectively; and a plurality of battery modules accommodated in the first and second battery accommodating portions (7, 8a, 8b) of the battery pack case, wherein a first side air flow path for allowing air sucked through the air-suction portion to flow therethrough is formed between one of opposite sidewalls of the battery pack case and opposing battery modules, the first side air flow path being in communication, at its first region and second region (14, 15), with the first and second battery accommodating portions (7, 8a, 8b) of the battery pack case, respectively, the junction box accommodating portion is covered with a shield member (21, 22, 23, 23a, 23b), and the shield member is configured to prevent air that is supplied from the air-suction portion and flows along the first region of the first side air flow path from flowing into the junction box accommodating portion and guide air from the first region of the first side air flow path along the shield member to the second region (14, 15) of the first side air flow path.