The population of this study was 123 companies which are located at Daeheung - dong, Mapo - ku, Seoul and have more than 30 employees/statistics data of Mapo-ku Office, April 11, 2000), and the subject of this study was 472 female and male workers chosen among ten of this population with each granted a optional number by random sampling. The instruments of this study were the basic background questions which set each question for sex, age, exercises participation hours, frequency, type of exercises, and the SCL - 90 - R(Symptom Checklist - 90 - Revision) test sheets which were originally made as "Multimensional Self - Report Symtopm Inventory" by Derogatis, Cleary, et al.(1977) and standardized in 1984 after once called "Simple Mental Diagnosis & Test" by Kwang-il, Kim and Ho-taek, Won(1978) in Korea. As the statistics process, after SCL-90-R, scores were recorded in ‘Never(4-point)’, ‘Little(3-point)’, ‘Moderate(2-point)’, ‘Serious(1-point)’, and ‘Very level of significant meaning in order to investigate the difference among mental health indexes of participants and non-participants in morning exercises and the difference according to sex among participants in morning exercises, and one-way ANOVA, of 5% level of significant meaning in order to examine the differences of mental health indexes according to age, frequency, and type of exercises. And for post verification, Duncan's method of post verification was used. On the basis of the above research procedures and results of data analysis, the conclusion of this study is drawn as following: First, comparing the differences of mental health indexes among participants and non-participants in morning exercises, it was found that the mental health indexes of participants in morning exercises were higher in the subscales of somatization(SOM), obsessive-compulsive(O-C), interpersonal-sensitivity(I-S), hostility(HOS), paranoia(PAR), psychosis (PSY), and that there was no meaningful difference in the subscales of depression(DEP), anxiety(ANX), and phobia(PHOB). Second, comparing the difference of mental health indexes among participants in morning exercises and exercises after work, there was no meaningful difference in the mental health subscales of somatization, obsessive-compulsive, interpersonal-sensitivity, depression, anxiety, hostility, phobia, paranoia, and psychoticism. But it was found that participants in morning exercises recorded a little bit higher mental health indexes in general. This revealed that morning exercises can be more beneficial for workers' mental health than exercises after work. Third, comparing the differences of mental health indexes according to each variable(sex, age, frequency, type of exercises), there was no meaningful difference in all mental health subscales in the case of comparison of the difference of mental health indexes according to sex. In the case of the difference according to age, ‘21 - 30 ages’ recorded the highest in SOM, followed by ‘31 - 40 ages’, ‘51 - 60 ages’, and ‘41 - 50 ages’, and ‘31 - 40 ages’, the highest in O - C, followed by ‘41 - 50 ages’, ‘51 - 60 ages’, and ‘21 - 30 ages’. In addition, ‘31 - 40 ages’ recorded the highest in I-S, followed by ‘41 - 50 ages’, ‘51 - 60 ages’, and ‘21 - 30 ages’, and ‘31 - 40 ages’, the highest in HOS, followed by ‘41 - 50 ages’, ‘21 - 30 ages’, and ‘51 - 60 ages’. There was no significant difference in DEP, ANX, PAR, and PSY. And in the case of comparing mental health indexes according to frequency, ‘3 to 4 times per week’ recorded the highest in SOM, followed by ‘5 to 6 times’, ‘1 to 2 times’, and everyday, and ‘3 to 4 times per week’, the highest in O-C, followed by ‘5 to 6 times’, ‘everyday’, and ‘1 to 2 times’. ‘3 to 4 times per week’ recorded the highest in ANX, followed by ‘5 to 6 times’, ‘everyday’, and ‘1 to 2 times’, and there was no significant difference in I-S, DEP, HOS, PHOB, PAR, and PSY. Meanwhile, it is found that there was no difference according to type of exercises in comparing mental health indexes according to type of exercises, and it revealed that there was no relationship between type of morning exercises and mental health.