An application that assists the beginners to learn logic circuits is proposed. A logic circuit is drawn by handling a mouse to select various logic elements provided with menu screen, and to connect them with lines on the display. When the timing simulation is executed, the operation situation of the making circuits are easily understood because from input end to output end they are displayed in red if it is true (1), and in blue if it is false (0). And then, by those timing charts the logic relations of the drawn circuits can be verified.