Mushroom growing media waste (MGMW) is the media waste after mushroom plants are harvested. In this research, we try to reuse MGMW as a material for composite particle board. The physical properties of the composite were tested using density and moisture content measurement. We also did the measurement for thickness swelling after immersion in water, the strength of absorption water, internal bonding. The mechanical test was conducted to know the modulus of elasticity, modulus of rupture and screw holding power properties. Impact and pressure was done for the optimum composition. The optimum composition, particle board is 75% MGMW + 24% polyester resin + 1% catalyst Mekpo (methyl ethyl ketone peroxides), and 60% MGMW + 39% (50% urea +50% starch) + 1% PVC glue. It is suitable for physical and mechanical test and accordance with SNI 03-2105-2006 and JIS A 5908-2003. The microstructure of MGMW was observed using Scanning Electron Microscope (SEM) shows the grain of a composite particle board is firmly integrated.