A process for preparation of silver oxide with various shape and size using a silver complex compound having a special structure, includes 1) step of preparing a precursor solution including a silver complex compound obtained by reacting a silver compound with one or more mixture selected from the group consisting of an ammonium carbamate-based compound, an ammonium carbonate-based compound or an ammonium bicarbonate-based compound in the presence of a solvent; and 2) step of preparing silver oxide by reacting the precursor solution including the silver complex compound of step 1) with an oxidant. The shape and particle size of the silver oxide prepared according to the preparation process can be changed.