Disclosed is method for preparing ripe persimmon directly on a persimmon tree, comprising the steps of preparing a sealing cover (S1); providing an ethylene generator for generating ethylene gas in the sealing cover (S2); receiving each persimmon, which is dangled on the tree, with the sealing cover in which the ethylene generator is provided (S3); aging the persimmons for a desired period of time in the sealing cover and thus forming the ripe persimmon (S4); and removing the sealing cover and then cleaning the ripe persimmons (S5). Therefore, the ripe persimmons having a good taste and freshness can be simply and efficiently manufactured.