The purpose of this study was to find the effects of the lumbar stabilizing exercise on the isometric lumbar extension strength and the range of motion of lumbar extension. 16 healthy subjects were recruited (9 males, 7 females, mean age 25${pm}$3.2). They performed 5 types of exercises 5 times per week for 4 weeks. We evaluated isometric trunk extension strength (0, 12, 24, 36, 48, 60, $72^{circ}$) by MedX(Ocala, FL) and measured range of motion of lumbar extension. All measurements were measured at pre-exercise and 4 weeks post-exercise. The results of this study were summarized as follows; After 4 weeks of exercise, isometric lumbar extension strength was generally increased but there were only significant differences at $12^{circ},;24^{circ},;48^{circ}$. The range of motion of lumbar extension was increased (p<.05). The isometric lumbar extension strength correlated with the range of motion of lumbar extension. In conclusion, our results have shown that lumbar stabilizing exercise influenced both lumbar extension strength and range of motion of lumbar extension.