Strombus canarium is the gastropod in the Family Strombidae. It is the eatable species and popular for human consumtion. This study is to investigate the gonad of S. canarium collected from Sriboya and Pu Island at Krabi province in a period of two months between June to July 2007. The sections of ovary and testis were stained with hematoxylin&Eosin(H&E) and Mollary’s trichome. Male’s sperm is dimorphism. The fertile sperm is eusperm, nonfertile sperm is parasperm. Euspermatogenic cell can be classified into 4 stages: euspermatogonium, primary & secondary euspermatocyte and euspermatozoa. Paraspermatogenic cell was classified into 3 stages: paraspermatocyte, paraspermatid and paraspermatozoa. In female the oogenic cell consists of 4 stages: oogonium, pre-vitellogenic oocyte, vitellogenic oocyte and mature oocyte. The process of gonadal development was classified into 6 stages. The details of all stages were described in this study.