A heat accumulator, in particular latent-heat accumulator, has an inner casing containing an accumulator core and with an outer casing enclosing the inner casing at a distance thereto so as to form an insulation space, the insulation space being baked out and evacuated. The inner casing has a pipe connection with a fill opening through which the storage medium can b introduced and which can be closed by a mechanical closing element after the storage medium has been introduced. The outer casing has a pipe connection with a fill opening through which the insulation space can be filled with insulating medium and or evacuated and which can be closed by a mechanical closing element. The pipe connection of the inner casing is disposed coaxially to the pipe connection of the outer casing. This simplifies manufacture of the heat accumulator.