PURPOSE: To provide a lawn grass cutting and drainage device having a simple mechanism by cutting lawn grass by an iron-working knife unit which is loaded on a trailer tracted by a motive power unit such as a rubber tire or the like and capable of freely oscillating and boring a cavity to bury a pipe with pumice.

CONSTITUTION: A cavity is bored in a groove by an iron working knife unit 4 and an earth removal machine 10 flexibly connected to the knife unit by a link 20. Surplus soil discharged by the iron-working knife unit 4 and the earth removal machine 10 is taken in a hopper 5 by a discharge machine 33, and a pipe is buried in the rear of the earth removal machine 10. Pumice 51 for backfilling the buried pipe 9 is equally dropped from a dispersion port 52 and treaded down by a tread pressure roller 12.