A snap ring having an easily replaceable support reliably supports a purse line and overcome frictional force between the purse line and the snap ring even without having a side roller requiring a complex structure on an end of a main roller. In the snap ring, in lieu of a side roller having a complex structure, the support having a simple structure is provided in at least one of the first and second side parts of a frame such that the support and the main roller can reliably support a purse line and overcome frictional force between the snap ring and the purse line. Furthermore, each of the support and the main roller is configured so as to be separately replaceable with a new one. Thus, even if the support or main roller becomes worn, it can be easily replaced with a new one.