In the acquisition or disposal of assets, onerous and gratuitous transactions are admixed with each other whether it is executed at a high price or a low price. Thus, it is complicated to address the matter on tax system. Accordingly, it requires that the tax system, relevant to low-price and high-price acquisition or disposal, should be reformed. The followings show their drawbacks and remedies. First, in case a business proprietor acquires assets at a low price and disposes of them subsequently, the original cost should be calculated on the basis of the actual acquisition cost under current law. However, it may wrongfully infringe upon taxpayers` property rights, wherefore it is advisable to modify relevant regulations. Second, in cases where a private person transfers to an affiliate person at a high price, there has been an interpretational controversy about the transfer price. In this regard, it is valid to take the whole amount into the transfer price but to exclude it from gift tax. Third, there is a need to modify the regulations against the rejection of unfair act and calculation, which may enable the correlative adjustment of the opposite party as well as the prevention of double taxation. Fourth, there is no plausible reason to treat the securities, acquired by a corporation from an affiliate person, differently from any assets else, whereupon there is a need to modify relevant regulations in order that corporations may dispose of such assets, here as elsewhere, and may pay the tax at the time of income realization. Fifth, the current law addresses gift tax separately from income tax. Surely, it is reasonable to charge gift tax on donated assets. On the other hand, income tax should be charged on cases where on which gift tax may not be charged. Hereat, it is advisable to modify relevant regulations. Sixth, with regard to low-price acquisition or high-price disposal, it is stipulated in Article 35 of Inheritance Tax and Gift Tax Act that the acquirer or disposer shall pay gift tax on the difference between the market price and the cost. It is problematic to reckon the stipulation to be legitimate, and also there have been very few cases of practical application. As the case stands, it is advisable to abolish the stipulation. Lastly, with regard to the profit made by listed stocks or shares, the transfer income tax should be imposed when the stocks or shares are sold. Thus, there is a need to modify relevant regulations. This study is expected to be helpful to reasonably modify tax laws relevant to low-price and high-price acquisition or disposal of assets.