A battery pack comprising battery cells or unit cells that can be charged and discharged, wherein the battery pack is configured to have a structure in which a plurality of the unit cells constitutes a battery module, two or more of the battery modules are vertically arranged in a height direction, which is the vertical direction, of the battery pack from a coolant introduction direction of a coolant inlet port to constitute a pair of battery module groups, a flow space, which is a coolant introduction part, extending from the coolant inlet port to each battery module group is provided at a middle of a pack case in a state in which the coolant introduction part is located between the respective battery module groups, flow spaces, which are coolant discharge parts, extending from the respective battery module groups to coolant outlet ports are provided at an upper part and a lower part of the pack case, and a coolant flow channel defined between the coolant introduction part and the coolant discharge parts is configured to have a structure in which a coolant, introduced through the coolant introduction part, passes by each unit cell to cool each unit cell, and is discharged through the respective coolant discharge parts, wherein the battery module groups, which are an upper battery module group and a lower battery module group, are respectively arranged at an upper side and a lower side of the coolant introduction part and the coolant flow channel is divided in the coolant introduction part in a width direction of the battery pack such that the coolant is introduced into the upper battery module group and the lower battery module group, and wherein a division member, which is configured to have a structure in which a distance from each battery module group is decreased toward an end of the coolant introduction part opposite to the coolant inlet port, is mounted in the coolant introduction part, wherein the pack case is configured to have a structure in which a top and/or a bottom of the pack case comprises two or more continuous inclined surfaces, wherein a distance between the division member and the respective battery module groups is adjusted in an inverse proportional relationship in response to a ratio of a height of an upper coolant discharge part formed at the upper part of the pack case to a height of a lower coolant discharge part formed at the lower part of the pack case, and characterized in that the division member is provided at surfaces thereof corresponding to an end opposite to the coolant inlet port with irregularities. a plurality of the unit cells constitutes a battery module, two or more of the battery modules are vertically arranged in a height direction, which is the vertical direction, of the battery pack from a coolant introduction direction of a coolant inlet port to constitute a pair of battery module groups, a flow space, which is a coolant introduction part, extending from the coolant inlet port to each battery module group is provided at a middle of a pack case in a state in which the coolant introduction part is located between the respective battery module groups, flow spaces, which are coolant discharge parts, extending from the respective battery module groups to coolant outlet ports are provided at an upper part and a lower part of the pack case, and a coolant flow channel defined between the coolant introduction part and the coolant discharge parts is configured to have a structure in which a coolant, introduced through the coolant introduction part, passes by each unit cell to cool each unit cell, and is discharged through the respective coolant discharge parts, wherein the battery module groups, which are an upper battery module group and a lower battery module group, are respectively arranged at an upper side and a lower side of the coolant introduction part and the coolant flow channel is divided in the coolant introduction part in a width direction of the battery pack such that the coolant is introduced into the upper battery module group and the lower battery module group, and wherein a division member, which is configured to have a structure in which a distance from each battery module group is decreased toward an end of the coolant introduction part opposite to the coolant inlet port, is mounted in the coolant introduction part, wherein the pack case is configured to have a structure in which a top and/or a bottom of the pack case comprises two or more continuous inclined surfaces, wherein a distance between the division member and the respective battery module groups is adjusted in an inverse proportional relationship in response to a ratio of a height of an upper coolant discharge part formed at the upper part of the pack case to a height of a lower coolant discharge part formed at the lower part of the pack case, and characterized in that the division member is provided at surfaces thereof corresponding to an end opposite to the coolant inlet port with irregularities.