The study analyzes the development of slim-fit formal pants patterns for middle-aged men. This study suggests a new pattern that complements the problems of the existing fit on the basis of the standard nude size for middle-aged men with lower garments through the analyses of one-tuck pants patterns from 5 popular brands. As a result, the waistline is lowered by 0.8cm out of consideration for the waist circumference. The crotch extension is reduced by 1.5cm, the back crotch length is revised, the center back waist point is raised by 0.9cm, and the hip line is straightened. The slim-fit is perfected of the new lines from the thigh to knee-line.