The Test of Gross Motor Development-II (TGMD-II) is a frequently used assessment tool for measuring motor ability. The purpose of this study is to investigate the reliability and validity of TGMD-II's weighting scores (by comparing pre-weighted TGMD-II scores with post ones) as well as examine applicability of the TGMD-II on Korean preschool children. A total of 121 Korean children (three kindergartens) participated in this study. There were 65 preschoolers who were 5-years-old (37 boys and 28 girls) and 56 preschoolers who were 6-years-old (34 boys and 22 girls). For internal consistency, reliability, and construct validity, only one researcher evaluated all of the children using the TGMD-II in the following areas: running; galloping; sliding; hopping; leaping; horizontal jumping; overhand throwing; underhand rolling; striking a stationary ball; stationary dribbling; kicking; and catching. For concurrent validity, the evaluator measured physical fitness (strength, flexibility, power, agility, endurance, and balance). The key findings were as follows: first, the reliability coefficient and the validity coefficient between pre-weighted and post-weighted TGMD-II scores were quite similar. Second, the research showed adequate reliability and validity of the TGMD-II for Korean preschool children. The TGMD-II is a proper instrument to test Korean children's motor development. Yet, applying relative weighting on the TGMD-II should be a point of consideration.