The deal, aimed at promoting and protecting two-way investment, will mark one of the biggest breakthroughs in Taiwan-Japan ties since Tokyo switched recognition to Beijing in 1972, Taiwan media said on Wednesday.
Japanese companies will be given the same rights as local firms so they can invest in Taiwan without the restrictions imposed on other foreign companies and vice versa, according to the Taipei-based United Daily News.
The pact will also pave the way for Taiwan and Japan to sign a broader free trade agreement in the future, the paper said.
The de facto Japanese embassy in Taiwan confirmed that there has been "big progress" in the planned deal, but did not elaborate.
The two sides reportedly will sign the agreement as soon as Thursday when Mitsuo Ohashi, the head of Interchange Association Japan, is due arrive in Taipei for a visit.
The association handles unofficial ties with Taiwan in the absence of formal diplomatic relations.
Taiwan has been pushing for closer trade ties with Japan, particularly following the signing of a major trade pact with China last year.
Japan is Taiwan's second largest trade partner after China.
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