© 2015, Fuji Technology Press. All rights reserved. The present study shows the possibility of using Xband multi-parameter radar to detect volcanic tephra for estimating the amount of volcanic tephra in the air even when the amount of volcanic tephra is very low. The model proposed in this study can detect tephra with diameters of 0.5mmto 3 mm. Through the observation experiment and the model proposal, the present study shows successful detection of volcanic tephra in the air by using X-band multi-parameter radar.