This study aims to compare student self-, teacher-, and objective assessments of elementary science-gifted students' scientific creativity. A science-gifted program on the topic of Hydraulic Machine was implemented to 40 fifth-graders in the Science-Gifted Education Center of an education office in Seoul, Korea for four weeks. The products of the students' activities were assessed by three types of 'Student Self-Assesment', 'Teacher-Assesment', and 'Objective Assessment using Formula'. Based on two essential components of creativity, the scientific creativity is divided into two parts of originality and usefulness. Ideas that satisfy both components can be counted as scientifically creative. The main results of this study are as follows: First, the scores of each week and the average of the overall four-week scores on scientific creativity were significantly correlated. Student self-assessment (r=.687), teacher-assessment (r=.715), and objective assessment (r=.724) appeared consistently over instructional periods. Second, the average scores of student self-, objective, and teacher-assessments were 73.15, 35.72, and 26.60, respectively. The result of student self-assessment on scientific creativity tended to be higher than those of formula and teacher. Third, among the three types of assessment on scientific creativity, a strong correlation appeared between teacher- and objective assessment (r=.974), but neither between student self- and objective (r=.161) nor between student self- and teacher- (r=.213). Fourth, the scores on originality component had a positive correlation between teacher- and objective assessment (r=.713). The scores of student self- and teacher-assessments had a significant correlation too (r=.315), but not between student self- and objective assessment (r=.279). Fifth, the scores on usefulness component did not have a significant correlation between student self- and teacher-assessment (r=.155). Sixth, there was no significant difference on scientific creativity between student self- and objective assessment [${\chi}^2$(1, n=40)=1.667, p<.197]. Not between student self- and teacher-assessment either [${\chi}^2$(1, n=40)=1.616, p<.204]. On the contrary, there was a significant difference between teacher- and objective assessment [${\chi}^2$(1, n=40)=32.593, p<.000]. Seventh, the students were categorized into four groups according to the levels of their scores by student self- and teacher-assessment. The result showed that factors influencing student self-assessment are inherent in the personality traits of gifted individuals, such as self-esteem and perfectionism. The findings suggested that there are challenges for the educators to make efforts to construct consistent assessment methods for scientific creativity.