The present application relates to a preparation method for solid powder of a carbamic acid derivative, which includes reacting an amine derivative with carbon dioxide at a temperature in a range of from about −30° C. to about 500° C. and at a pressure in a range of from about 0.3 MPa to about 100 MPa. In addition, the present disclosure relates to a reduction method for solid powder of a carbamic acid derivative to an amine derivative and carbon dioxide, which includes dissolving solid powder of the carbamic acid derivative prepared in a solvent; refluxing the carbamic acid derivative at a temperature in a range of from about 30° C. to about 100° C.; and evaporating the solvent.