I will present the analysis of the event OGLE-2019-BLG-0726: a very low mass ratio planetary event found by gravitational microlensing. By analyzing the light curve obtained from dense survey observations, I found that the best-fit mass ratio is q~10-5 , which is lower than the mass ratio of any published microlens planet. This event contributes to the sample of low mass ratio microlens planets found below the peak of mass ratio function (~6e-5) found by Suzuki et al. (2016) and Jung et al. (2019), so will aid in the determination of the slope of the function. The Roman Space Telescope will conduct the microlensing survey from the space and should be able to study the exoplanet distributions with mass ratio as small as q~10-7, which is 3 times smaller than the Mars-Sun mass ratio.