The purpose of this study is to investigate the changes in the inadequate labor force sector of Taiwan before and after the coming Knowledge-Based Economic Time, which is considered as important to this study. The inadequate labor force sector mentioned above consists of inadequate working hours, low paid and mismatches between educational attainment and occupation. The raw data been used was from Manpower Surveys and Manpower Utilization Surveys Taiwan area, Republic of China by Census Bureau in both year 1991 and 2003. The study reveals the following findings. 1.In the inadequate working hours portion Workers who are male, age 35 to 44, married or cohabited, highest educational attainment is primary school or below, private-sector employed, working in north area of Taiwan and taking the roles as agriculture, animal husbandry, forestry & fishing and craft & related trades workers are significantly easier to fall into the inadequate working hours sector. 2. In the low paid portion Workers who are male, married or cohabited, highest educational attainment is primary school or below, own-account workers, workplace is located in middle area of Taiwan, agricultural, animal husbandry, forestry & fishing workers are significantly easier to fall into the low paid sector. 3. In the portion of mismatches between educational attainment and occupation Workers who are male, age 25 to 34, married or cohabited, highest educational attainment is senior high school & vocational school or above, private-sector employed and working in north area of Taiwan are significantly easier to fall into this sector. Especially, workers who take the roles as prod., machine operators and related workers, plant & machine operators & assemblers , and manufacturing share a large proportion. According to the conclusions above, this study provides typical suggestions for government polices toward utilization of labor force. The given comments will be helpful to the relative researchers in the further.