Changes of free amino acids, nucleotides and their related compounds as taste compounds during sun drying of ascidian Cynthia roretzi, were analyzed by amino acid autoanalyzer and high speed liquid chromatography. In fresh ascidian, the results showed that 5'-UMP $(12.1\;{\mu}mole/g)$ was dominant and the content of cytosine, 2', 3'-CMP, 2', 3'-GMP, hypoxanhtine, 5'-AMP,5'-IMP were 5.8, 3.4, 3.1, 2,3, 1.7 and $1.3\;{\mu}mole/g$ ondry base respectively. 5'-IMP, 2', 3'-CMP and 2', 3'-GMP tended to degrade slowly and 5'-AMP, cytosine and 5'-UMP were decreased rapidly while hypoxanthine were increased remarkably during the sun drying. In dried ascidian, the content of hypoxanthine was the highest, 7.2 mole/g on dry base, whereas that of 5'-AMP $(0.5\;{\mu}mole/g)$) and 5'-IMP $(0.9\;{\mu}mole/g)$ were lower. Glutamic acid, alanine and serine were dominant amino acid in the fresh extracts, having 22.4% (611.3mg%, on dry qase), 19.8% (540.5mg%) and 14.8% (402.8mg%) of the total amino acid content respectively. The content of tyrosine, histidine, lysine, methionine, isoleucine and valine were low, and proline, phenylalanine were detected in trace amount. The free amino acid were not changed in composition but the increase of total free amino acid was approximately 116.8mg% during sun drying. In sun dried ascidian, glutamic acid (691.0mg, on dry base), alanine (641.3mg%), serine (469.5mg%), threonine (234.8mg%) and glycine (206.3mg%) were dominant amino acid. It is believed that glutamic acid, serine, alanine, threonine, glycine and hypoxanthine play an important role as taste compounds in sun dried ascidian.