The surface grating technologies enable to control the thermal radiation spectrum. We are applying this technique to promote the chemical reaction to produce hydrogen in the methane steam reforming process by spectrally resonant thermal radiation. The thermal radiation spectrum is adjusted to the vibrational absorption bands of methane and water molecules near 3μm by making two-dimensional (2D) microcavities with the period Λ=2.6 μm on the radiative surface. By tuning the peak of thermal radiation to the absorption bands of these gases, it is clearly observed that the methane steam reforming is promoted by using spectrally selective emitter. Since the promotion of hydrogen production can be observed under resonant excitation of gases, it is suggested that the optical excitation of vibrational levels is contributed to this phenomenon. From the result, it is confirmed that the thermal radiation resonant with molecular absorption bands is effective to the high production rate of hydrogen in methane steam reforming process. To study the detail process of chemical reaction, under resonant excitation, the produced gas is analyzed by gas chromatograms.