The assumption that vocational aptitude changed with age and with the kind of occupation was examined from the tendency of the fitted curve for the score of the aptitude test. 9 vocational aptitudes were measured by the general vocational aptitude test by Japan Labor Ministry. Subjects were 382 male workers (design engineers, turners, welders, can manufacturing workers, and crane operators) of from 20 to 59 years old, and 348 male and female students (junior high school, vocational school, and university) of from 15 to 19 years old. The design engineers' aptitudes advanced along the quadratic curve until 31 years old, but almost all the aptitudes of the other workers fell along the linear curve with age. The design engineers preserved various aptitudes until 52 years old, the turners 44, and the welders, the can manufacturing workers, and the crane operators 37. The students' aptitudes were equal to those of the workers of from 15 to 25 years old. The workers preserved Spatial aptitude and Numerical aptitude until 45 years old. This could be said in all the occupations here. Further it was made clear from the micromotion study that the influence of age was caused by therbligs