1. A method of designing a logic circuit using a computer comprising the steps of: a) inputting in the form of a table for hardware implementation a description of logic specification in which a setting condition of a signal and a behavior of the logic circuit are described in a corresponding relation to each other as a behavioral specification of the logic circuit each being composed of at least one equation described by combining at least one type of a constant, a variable, a logical operator, a relational operator and an arithmetic operator said behavior of the logic circuit which is executed when said signal setting condition is satisfied; b) forming a Boolean expression corresponding to a selector for selecting an output of a logic circuit constructing said behavior description as a data signal on the basis of a selection signal which is generated from a logic circuit corresponding to the equation constructing said setting condition description when said signal setting condition is satisfied; c) registering said condition and said relational operator and/or arithmetic operator as described in said condition and said behavior into a library which has previously been prepared and allocating a regular logic circuit corresponding to a function of the operator expressed by a Boolean expression; and d) detecting and eliminating a redundancy logic included in the logic circuit whose function is expressed by the Boolean expression and which includes the selector and the regular logic circuit.