It was successfully decided that the ΛΛ interaction was weakly attractive, by the E373 (KEK-PS) experiment with hybrid-emulsion method, recently. To get systematic understanding for double strangeness system, the experiment E964 has been approved at BNL-AGS. The experiment should provide us one hundred samples of light and heavy double-hypernuclei and information for the existence of the H dibaryon resonance. We will also get the first data of X-ray from Ξ--atom which shall give us information of Ξ--nuclear potential.