Disclosed herein is an atomic layer deposition apparatus including a reaction chamber provided with a chamber inlet, through which an inert gas or a precursor gas, which is a mixture of the inert gas and a gas-phase precursor, is introduced into the reaction chamber, and a chamber outlet, through which gas is discharged from the reaction chamber, a gas supply device provided with a gas supply pipe, along which an inert gas is supplied, a precursor storage having a precursor for generating a precursor gas to be supplied to the reaction chamber received therein, the precursor storage being provided with an inlet, through which the inert gas supplied along the gas supply pipe is introduced into the precursor storage, and an outlet, through which the precursor gas is discharged from the precursor storage, a first storage connected to the chamber inlet for temporarily storing an inert gas or a precursor gas to be supplied into the reaction chamber, a first valve located at an outlet of the first storage for contro
