Example embodiments relate to an energy harvester using triboelectricity, and to an apparatus including the energy harvester. The energy harvester may include a first structure having a first triboelectric material, a second structure having a second triboelectric material, and a closed structure isolating friction surfaces of the first and second triboelectric materials from external environment. The energy harvester may further include a filling material in the closed structure. The filling material may have an electric charge. The filling material may have a viscosity. At least a portion of the closed structure may include an elastic material.