Emission spectra of the a　1Δg(v=1)→X3Σg-(v=0) transition of the singlet molecular oxygen 1O2 produced by hematoporphrin(HP) in solutions of water, acetone and ethylalcohol were measured with Ar+ laser as the pumping light source. The relative phosphorescence intensity (relative value of the 1O2 quantum yield) was found to depend on the pumping power, concentration of HP and pumping light wavelength. The quenching effect of ascorbic acid (injected as a quencher) on the singlet molecular oxygen was observed.