A battery pack comprising: a plurality of batteries ; a thermally conductive plate having two opposite principal surfaces connected by side surfaces , said thermally conductive plate being in contact with the plurality of batteries ; and a case which houses the plurality of batteries and the thermally conductive plate , wherein the case includes a grip part which is not in contact with a side surface of the thermally conductive plate , wherein the grip part regulates displacement of said two principal surfaces of the thermally conductive plate in a direction orthogonal to said two principal surfaces , the grip part being in contact with at least one of the two principal surfaces , and thereby holding an end part of the thermally conductive plate , and wherein the grip part includes a slit in which the end part of the thermally conductive plate is inserted, wherein the grip part is in contact with at least one of the two principal surfaces of the thermally conductive plate via at least one of two facing surfaces of the grip part , wherein the two facing surfaces define the slit, wherein the grip part is not in contact with the side surface via a surface of the grip part which connects the two facing surfaces which define the slit, characterized in that the thermally conductive plate and the grip part are configured such that the thermally conductive plate is detachable from the grip part by sliding in the slit the thermally conductive plate with respect to the grip part , and the battery pack further comprises a grease which connects the surface which connects the two facing surfaces which define the slit, and the side surface of the thermally conductive plate . a plurality of batteries ; a thermally conductive plate having two opposite principal surfaces connected by side surfaces , said thermally conductive plate being in contact with the plurality of batteries ; and a case which houses the plurality of batteries and the thermally conductive plate , wherein the case includes a grip part which is not in contact with a side surface of the thermally conductive plate , wherein the grip part regulates displacement of said two principal surfaces of the thermally conductive plate in a direction orthogonal to said two principal surfaces , the grip part being in contact with at least one of the two principal surfaces , and thereby holding an end part of the thermally conductive plate , and wherein the grip part includes a slit in which the end part of the thermally conductive plate is inserted, wherein the grip part is in contact with at least one of the two principal surfaces of the thermally conductive plate via at least one of two facing surfaces of the grip part , wherein the two facing surfaces define the slit, wherein the grip part is not in contact with the side surface via a surface of the grip part which connects the two facing surfaces which define the slit, characterized in that the thermally conductive plate and the grip part are configured such that the thermally conductive plate is detachable from the grip part by sliding in the slit the thermally conductive plate with respect to the grip part , and the battery pack further comprises a grease which connects the surface which connects the two facing surfaces which define the slit, and the side surface of the thermally conductive plate . <EOS>