Saccharomyces cerevisiae J170, a mutant, was used for $DL-^{14}C-leucine$ uptake during the sporulation and vegetative stage. $^{14}C-Leucine$ uptake into yeast cells appeared the highest at pH 6.0, indicating the same result of glucose transport, $^{14}C-Leucine$ uptake in sporulation period was higher than in growth phase, showing the evidence that leucine is more required for protein synthesis. This tendency has the evidence tht leucine is more required for protein synthesis. This tendency has the evidence that leucine is more required for protein synthesis. This tendency has been also supported from the result of Km values of leucine uptake in two stages of yeast. Leucine uptake was inhibited by 2,4-dinitrophenol in two stages of yeast. This means that leucine transport system is associated with energy dependent in both stages. The contents of all amino acid in growth phase cells were higher than those of sporulation stge cells, and those of methionine and tyrosine were showed in trace during the sporulation stage. In contrast, the content of glutamic acid in sporulation stage was compared with those of other amino acids.