The World Society for Protection of animals and a Japanese charity called ALIVE have made a video that show how badly hundreds of bears are treated.
They aren't given enough food or space to live in, and aren't looked after properly when they're ill.
They're so hungry that when visitors throw food to them the bears fight for it, often hurting each other badly.
They've been investigating the parks for 12 years, but so far very little has been done.
The bears live in very cramped concrete pits and sometimes cubs born in them are killed and eaten by the older bears because they are kept so hungry.
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