Fourier transform infrad(FTIR) study was carried out on blend of poly ($\beta$ -hydroxy butyrate) (PHB) with poly(methyl methacrylate) (PMMA) and poly (methyl methacrylate-co-methyl hydroxymethyl acrylate) (PMHMA3 and PMHMA5) on solid state. Chloform and dimethylformamide(DMF)/chloroform(20/80 v/v) cosolvent were used for blending process. PHB/PMMA blend system is miscible but a little. PHB/PMHMA5 and PHB/PMHMA3 blend systems were enhanced miscibility by hydrogen bonding between carbonyl group of PHB and hydroxyl group of PMHMAs. Though a PMHMA3 molecules has more hydroxyl group than a PMHMA5 molecule, miscibility is less than PMHMA5 because PMHMA3 is easy to occur self association. Two different solvent have differnet effect on PHB/PMHMA3.