PURPOSE: To make a back hoe so as to be firmly attached to the rear part of a traveling car body.

CONSTITUTION: A symmetrical pair of hook parts 25, supporting an installing member 32 attached to the lower part of a frame 31 of a back hoe 30 after engaging it free of detachment from the upside, is installed at a rear part and beneath both symmetrical sides of a traveling car body 1. A symmetrical pair of boss cylinder 27 with a taper inserting hole 27A opened in both right and left directions and a position fitting 29 made into a rear open-form at the taper inserted side of these boss cylinder 27 are attached tight to right and left at the rear of the traveling car body 1 and in the point midway in a car level. In succession, a symmetrical pair of boss cylinder 35 with an internal thread 35A being fitted from the rear of the positioning fitting 29 and a symmetrical pair of taper pin 28 being feedably screwed in these paired cylinders 35 and taperifitted in the taper inserting hole 27A both are installed on top of the frame 31 of the back hoe 30.