(Ti_(1-x)Al_x)N coatings of constant as well as continuously changing Al concentrations were deposited onto M2 high speed steel(HSS) substrates by the ion-plating method, and the microstructure and adhesion strength of the coatings were investigated. The Al concentration could be easily controlled by using separate evaporation sources for Ti and Al, and changing the evaporation rate of the metals. With increase of Al concentration, the grain size decreased and the microstructrure of the coating became denser. Although the hardness of the coating increased by the structural effect, the adhesion strength decreased with the Al concentration. The adhesion strength could be considerably increased by changing the Al concentration in the coating continuously, as the abrupt stress change at the interface between the coating and the substrate could be minimized.