An object of the present invention is to provide a senescence retarding agent that delays the onset of senescence symptoms and extends longevity, and is superior in safety. The senescence retarding agent of the present invention that achieves the object is characterized by containing a plant fermentation product as an active ingredient, the plant fermentation product being a mixture of the following: (a) a koji mold-fermented product of one or more kinds of beans and/or cereals selected from the group consisting of barley, black soybean, red rice, black rice, adzuki bean, adlay, Japanese millet, foxtail millet, and millet； (b) a yeast- and/or lactic acid bacterium-fermented product of one or more kinds of fruits selected from the group consisting of mikan (mandarin orange), grape, apple, yama-budo (crimson glory grape), peach, kaki (Japanese persimmon), papaya, nashi (Japanese pear), watermelon, ume (Japanese apricot), fig, karin (Chinese quince), pumpkin, kumquat, yuzu (Chinese lemon), loquat, apricot, jujube, chestnut, matatabi (silvervine), and sumomo (Japanese plum) ； (c) a yeast- and/or lactic acid bacterium-fermented product of one or more kinds of root crops and/or potatoes selected from the group consisting of murasaki-imo (purple sweet potato), kikuimo (Jerusalem artichoke), carrot, onion, satsuma-imo (sweet potato), satoimo (taro), jinenzyo (Japanese yam), daikon (Japanese radish), akakabu (red turnip), gobo (burdock root), renkon (lotus root), yacon, yuri-ne (lily bulb), kuwai (arrowhead), ginger, garlic, and turmeric； (d) a yeast- and/or lactic acid bacterium-fermented product of one or more kinds of flowers and/or leaf vegetables selected from the group consisting of cabbage, shiso (perilla), mulberry leaves, dokudami (Korean houttuynia), yomogi (wormwood), kumazasa (kuma bamboo grass), and dandelion； (e) a yeast- and/or lactic acid bacterium-fermented product of one or more kinds of seaweeds selected from the group consisting of kombu (sea tangle), wak
