The artificial marble with good natural pattern and color in accordance with the present invention is prepared mixing ununiformly at least two liquid resins through a line mixer 1, feeding the ununiformly mixed resin on a moving steel belt 4 at a constant speed through a flexible hose 2 and an exit nozzle 3, and reciprocating the exit nozzle perpendicularly to the steel belt by a predetermined program for the exit nozzle to stop at different positions for different durations. The line mixer used in this invention is a Kenics type and has inner elements of eight or less than eight. A line mixer with four to eight elements can be more preferably used.