For clinical application of cis[((1R,2R)-1,2-cyclohexanediamine-N,N')bis(R.sup.1)]platinum(II) (R.sup.1 is an alkanoyloxy group having 6 to 20 carbon atoms), the present invention aims at providing a formulation which prevents layer separation and changes in viscosity, shows fine suspendability, and which is easy to handle during administration. The formulation of the present invention is a lyophilized a formulation for injection obtained by dissolving a cis[((1R,2R)-1,2-cyclohexanediamine-N,N')bis(R.sup.1)]platinum(II) in 2-methyl-2-propanol and lyophilizing this solution, which has a central particle size distribution of around 3-25 .mu.m and a D90% value of not more than 40 .mu.m.