A flexible package has a bendability effective to at least maintain the bendability of at least one flexible battery cell accommodated therein. The flexible package includes a support module disposed in a flexible body and including a first structural member, a second structural member and at least two cushioning members that define a space for accommodating the at least one flexible battery cell when the support module is under the binding force of the flexible body. When the flexible body and the at least one flexible battery cell bend, the stress acting on the at least one flexible battery cell is reduced by the first structural member, the second structural member and the at least two cushioning members. Therefore, electrode layers inside the at least one flexible battery cell are protected and the integrity, safety, cycle life and bendability of the flexible cell are improved.