There are disclosed a chamber plate for use in cell fusion comprising a plate of single crystal silicon on which a plurality of chambers for holding at least a pair of unit cells are formed in array, said chamber having at the bottom a plate having slits which do not pass cells to be held; and a process for producing a chamber plate for use in cell fusion which comprises forming chambers for holding cells in a plate of single crystal silicon by anisotropic etching or isotropic etching by chemical etching.