I think avaaid is correct; the source term is supposed to be "原則的評価方式," which refers to a group of fundamental valuation methods for unlisted companies, as opposed to a single method.

You'll notice that in this PDF (http://www.hp.jicpa.or.jp/specialized_field/pdf/2-2-1-2-2007... it's contrasted with 特例的評価方式, and that both umbrella categories point to specific valuation methods that should be applied within them (p. 8). On page nine, you can see the different valuation methods that fall under "原則的評価方式"; choice of valuation method depends on the size of the company.

This PDF
(http://www.hp.jicpa.or.jp/specialized_field/pdf/4-11-0-2e-20... which summarizes in English the options for valuing unlisted companies, translates some of these methods into English, but you'll notice that neither 原則的評価方式 nor 特例的評価方式 are translated. They are not methods in themselves, but rather descriptions of methods.

So I think the full translation would be "fundamental valuation methods for unlisted companies" or "fundamental valuation method for unlisted companies," depending on the grammar of the sentence you're working with.

HTH.

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Note added at 3 hrs (2010-12-14 17:04:36 GMT)
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Sorry, weird things happened with the links. Try these:

http://www.hp.jicpa.or.jp/specialized_field/pdf/2-2-1-2-2007...
http://www.hp.jicpa.or.jp/specialized_field/pdf/4-11-0-2e-20...