This paper presents a study on the effects of pressure angle on tooth deflection and root stress. The analyses of tooth deflection and bending moment at root fillet due to a concentrated load on a gear tooth with various pressure angles were carried out by the finite difference method (FDM) and the results were compared with those measured. The validity of this analysis method was confirmed and the effects of pressure angle on the tooth deflection and bending moment were made considerably clear. The approximate equations for the deflection and bending moment due to a concentrated load on a gear tooth with various pressure angles were derived on the basis on the calculated and measured results.