Korean sluicing requires the use of a copular ita ‘be’ unlike English. In explaining such a peculiarity, a (pseudo-)cleft analysis has strongly been proposed that Korean sluicing is derived from a cleft construction, rather than from TP-deletion. In order to examine the plausibility of the cleft analysis, this paper, based on the experimental syntactic method, explores acceptabilities of Korean sluicings, which were designed to vary depending on the three factors, such as the presence or the absence of a correlate in an antecedent clause, of the overt subject kukey ‘it’ in a following clause, and finally, of a case marker on a remnant. 110 participants were told to judge 64 sentences (including filler sentences) and two-way repeated measure ANOVA was performed using SPSS (ver, 25.0). The experiment result shows that the acceptability becomes significantly higher when a correlate and a case marker on a remnant occur enough to ameliorate island effects. Also, the presence of the subject kukey ‘it’was found to have an effect to facilitate parsing. These suggest that the uniform cleft analysis cannot account for the various types of Korean sluicing, rather necessitating non-uniform analyses for them.