Deep foundation excavator

The cantilever (10) has a first facing surface (a left side panel (11A) of the cantilever body (11) and a left side panel (14A) of the pulley mounting member (14)) and a second facing surface (a right side panel (11B) of the cantilever body (11) and a right side panel (14B) of the pulley mounting member (14)) that face each other in a direction (left-right direction) orthogonal to the longitudinal direction (front-rear direction) of the cantilever (10). A first lifting pulley (19) is disposed on the outer surface of the left side plate (14A) of the pulley mounting member (14), and a second lifting pulley (23) is disposed on the outer surface of the left side plate (11A) of the boom body (11). A first opening/closing pulley (21) is disposed on the outer surface of the right side plate (14B) of the pulley attachment member (14), and a second opening/closing pulley (30) and an opening/closing cylinder (31) are disposed on the outer surface of the right side plate (11B) of the boom body (11). 悬臂(10)具有在与悬臂(10)的长度方