Structural dependence of intersubband absorption of the In0.53Ga0.47As/GaAs0.5Sb0.5 multiple quantum well structure lattice-matched to InP substrates was studied. A clear intersubband absorption with a narrow spectral linewidth was observed at room temperature. The conduction band offset Delta E-c was estimated to be 0.36 +/- 0.03 eV from the InGaAs well width dependence of the peak energy of the intersubband absorption spectrum. Based on the results obtained from the intersubband absoprtion, an InGaAs/GaAsSb double barrier resonant tunneling diode was fabricated, which shows a clear negative differential resistance at room temperature