This research was to examine the effects of various cyclodextrins on the solubility and stability of prodigiosin in seawater. Among them, ${eta}$-cyclodextrin was found to have the best efficiency and formation of the inclusion complex was saturated when prodigiosin and ${eta}$-cyclodextrin were mixed in a ratio of 1:8 and shaken at $25^{circ}C$ and pH 8.0 for 6 h. The maximum algicidal activity against Chattonella antiqua using the inclusion complex stored at $4^{circ}C$ for 5 weeks of culture was obtained, $52.28{pm}3.41%$, which was about 5.0 fold higher than that of control. Our results suggest that inclusion complexes of prodigiosin and ${eta}$-cyclodextrin could serve as effective algicidal agents.