The tools with which the deceased transfer their property to their heirs have varied. How to define free gifts in calculating legal reserve of inheritance in these various property successions is an important issue. In this Essay, I direct attention to the concept of ‘free gifts’ stipulated in Article 1113 of the Civil Act. I noticed the ways of calculating the amount of legal reserve of inheritance in which multiple parties participates especially in trusts. A trust is a legal relationship involving multiple parties so it has a similar aspect to a contract in favour of third person. But the beneficiary of the trust who is often called equitable owner in common law system has a stronger position than that of a simple creditor. Therefore it should be deemed that the value of the beneficial interest has been donated directly by the truster to the beneficiary when a property is transferred using a trust. Inter-vivos trust as will substitute is often substantively a gift mortis causa granting beneficial interest in trust to a beneficiary. As such, it is reasonable to include the value of the beneficial interest in the base property in calculating reserved share. And it should be allowed for the holder of revised share to claim for the return of it against the beneficiary by way of claiming the transfer of beneficial interest. In the case of trusts established by will, the beneficiary’s interest is calculated as a gift from the truster to the beneficiary. Therefore the value of the beneficial interest should be treated the same as the gift for the special beneficiary in calculating legal reserve of inheritance.