This study had been conducted to investigate the effect of some plant growth regulators inducing fruit enlargement and optimal harvest time in Sageretia thea. Two hundred fifty ㎎/ℓ mepiquat chloride treatment, 1㎎/ℓ thidiazuron treatment on full bloom, and 200㎎/ℓ gibberellic acid treatment on 7 days before full bloom resulted in the increase of 21.7% in weight, and 200㎎/ℓ gibberellic acid treatment 7 days before full bloom, 10㎎/ℓ forchlorfenuron treatment 14 days after full bloom, and 1㎎/ℓ thidiazuron treatment on full bloom also brought about positive effects on the enlargement of the fruit, increasing 6.3%, 6.3% and 8.1% in its transverse diameter, respectively. Furthermore, the effects of the plant growth regulator treatments on the harvest time of Sageretia thea were determined as follows: the increase in the optimal harvest time of 57.2 - 75.4%, shorter maturation period, by the treatments with 500㎎/ℓ mepiquat chloride 7 days after full bloom, 100㎎/ℓ gibberellic acid treatment on full bloom, 2.5㎎/ℓ forchlorofenuron 7 days after full bloom and 2㎎/ℓ thidiazuron treatment 7 days before full bloom; and the greater effects of plant growth regulator treatments on the fruit maturation in the following order, gibberellic acid > thidiazuron > forchlorofenuron > mepiquat chloride. The results of this study are expected to be used as a reference data to develop Sageretia thea as a new local specific crop for Jeju island.