To find out the desirable cryoprotectant for cryopreservation of bivalve trochophores, four types of cryoprotectant were tested with trochophores of the pearl oyster (pinctada fucata martensii) generally used in the pearl production in Korea. Each cryoprotectant (dimethyl sulfoxide, ethylene glycol, glycerol and 1,2-propanediol) was mixed with 0.2 M sucrose to make final concentrations of 0.01, 0.1, 1.0 and 2.0 M. The trochophores were immersed in each preparation, waiting for 10 minutes to reach equilibration and cryopreserved in the liquid nitrogen (-l96$^{circ}C$). Survival rate of trochophores thawed after cryopreservation increased as the media concentration increase. However, a few number of the trochophores seemed to be damaged with the efflux of cell inclusions. Our study rsults indicate that desirable cryoprotectants for cryopreservation of pearl oyster trochophores are 1.0~2.0 M dimethyl sulfoxide and ethylene glycol : 82.8~97.4% of the trochophores cryopreserved with these media survived after thawing.