Abstract: This paper reported a dermatitis which occurred among the workers in mussel farms.The incidence of the dermatitis wes 78% is the workers who worked on the sea.Through the investigation in worksite and scanaing electroa microscopy.the dermatitis was confirmed due to contacting with Nematocysts adhered to Sabellidea's shells that grew on the cultivating shelf of mussel.Preventive measures should be taken to avoid contacting with Sabellidea.