BATTERY PACK

A battery pack includes a battery cell; a main circuit board electrically connected to the battery cell; a flexible circuit board connected to the main circuit board and having an external connection terminal; a conductive compression layer between a first connection portion of the main circuit board and a second connection portion of the flexible circuit board, the conductive compression layer electrically connecting the first and second connection portion to each other, and including conductive particles and an insulating resin accommodating the conductive particles, wherein the first connection portion of the main circuit board includes a first insulating layer, first connection pads protruding from the first insulating layer, and accommodation spaces on the first insulating layer, between adjacent ones of the first connection pads and accommodating the insulating resin, and the second connection portion of the flexible circuit board includes second connection pads electrically connected to the first connection pads.