"This Roku" is kind of ambiguous as there's many models, but most of them use a USB power adapter, so if you have one that works on 220V and can supply at least 1 Amp then it will work. I think the Ultra power adapter, which isn't USB, also works on 220V.
Before you get one you may want to read this thread and the other multitude of complaints from people in the Philippines about how many channels/apps aren't available there:
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