In order to evaluate three species of diatoms as the live food sources for rearing larvae of sea urchin, Strongylocentrotus intermedius, six different feed experiments were conducted for 35 days. We measured sizes, survival rates on elapsed day after hatching and required days of each larval stages of sea urchin in the different feeding experiments. Sizes of the larvae of sea urchin cultured with Isochrysis + Chaetoceros, Isochrysis, Chaetoceros and Pavlova were $735{mu}m$, $718{mu}m$, $701{mu}m$ and $642{mu}m$, respectively. The highest daily growth rates of the larvae of sea urchin showed Isochrysis within 6 armed and Chaetoceros after 6 armed. Survival rates of the larvae of sea urchin cultured with Chaetoceros, Isochrysis + Chaetoceros, Isochrysis and Pavlova were $37.2\%,;35.0\%,;32.4\%,;and;18.4\%$, respectively. The required days from fertilization to the 8 armed (Senior) stage in the larvae of sea urchin, fed Chaetoceros, Isochrysis, Paviova, chaetocerost+pavlova, pavloua + Isochrysis and Isochrvsis + chaetoceros were 24, 27, 33, 28, 30 and 25 days, respectively.