The purposes of this study were to develop a rational and practical test for estimating the co-ordination ability of strength exertion (CASE) and to examine its statistical validity, reliability, and objectivity. Statistical reliability of the test was examined from both standpoints of the variation and the degree of correspondence of measurement values. Objectivity was examined from the correlation coefficient of measurement values by two testers. Validity was examined from two viewpoints as follows: 1) discrimination between different-ability-groups in nervous function, and 2) fall of CASE by drinking alcohol (See Table 1). The test method was form fitting the exertion value of grip strength (GS) to the demand value appeared on display of personal computer (PC). The test of CASE was performed using 2 kinds of description forms on display of PC: bar chart and wave. The demand values of bar chart and wave were sinusoidal wave form of 0.3 Hz and 0.1 Hz, respectively. Tracking wave was the range from 5% to 25% of maximal grip strength value. The variable estimating CASE was used the total of lags between the demand value and GS value. The findings on the test estimating CASE developed in this study can be summarized as follows: 1) The test has relatively high reliability and can estimate CASE with three trials. 2) The correlation coefficient of measurement values by two testers was significant (0.617-0.747). 3) The test can discriminate between different-ability-groups in nervous function. The biserial correlation coefficient showed significantly high value (0.631-0.931). 4) The test can discriminate between normal conditions and alcohol drinking conditions. Based on results obtained in 3) and 4), validity of the test seemed to be relatively high.