A battery pack comprising battery cells or unit modules, that is unit cells, that can be charged and discharged, wherein the battery pack is configured to have a structure comprising: a battery module group comprising one or more battery modules each having the unit cells mounted in a pack case in a state in which the unit cells are uprightly arranged in a width direction, that is a lateral direction, of the battery pack such that the unit cells are spaced apart from each other by a spacing distance for coolant flow; a coolant introduction part, as a flow space extending from a coolant inlet port to the battery module group, continuously defined in a space between a bottom of the pack case and the battery module group; a coolant discharge part, as a flow space extending from the battery module group to a coolant outlet port, defined in a space between a top of the pack case and the battery module group; an electronic member located at one side of the battery module group, the electronic member being mounted in an inner space defined by the coolant discharge part; and a coolant flow channel defined between the coolant introduction part and the coolant discharge part, the coolant flow channel being configured such that coolant introduced through the coolant inlet port cools the respective unit cells while passing through the respective unit cells and some of the coolant having passed through the respective unit cells cools the electronic member in an eddy form and is then discharged out of the battery pack through the coolant outlet port, characterized in that the electronic member is a battery management system, wherein the electronic member is located at an angle of 20 to 70 degrees to a direction in which the coolant flows from the coolant introduction part to the unit cells, wherein at least one communication port for coolant flow is defined between the electronic member and a corresponding one of the unit cells. a battery module group comprising one or more battery modules each having the unit cells mounted in a pack case in a state in which the unit cells are uprightly arranged in a width direction, that is a lateral direction, of the battery pack such that the unit cells are spaced apart from each other by a spacing distance for coolant flow; a coolant introduction part, as a flow space extending from a coolant inlet port to the battery module group, continuously defined in a space between a bottom of the pack case and the battery module group; a coolant discharge part, as a flow space extending from the battery module group to a coolant outlet port, defined in a space between a top of the pack case and the battery module group; an electronic member located at one side of the battery module group, the electronic member being mounted in an inner space defined by the coolant discharge part; and a coolant flow channel defined between the coolant introduction part and the coolant discharge part, the coolant flow channel being configured such that coolant introduced through the coolant inlet port cools the respective unit cells while passing through the respective unit cells and some of the coolant having passed through the respective unit cells cools the electronic member in an eddy form and is then discharged out of the battery pack through the coolant outlet port, characterized in that