To provide a demolition work assist unit eliminating the level difference of a connection part pipe in the operation area of a rotary cutter and also protecting vacuum ports during the operation of the rotary cutter.

This unit is composed of a pair of half cut cylinder bodies 21, 22. The half cut cylinder bodies 21, 22 are provided with storage portions 24 fastenably storing fastening members 23 for integrating the half cut cylinder bodies 21, 22 together. When both the half cut cylinder bodies 21, 22 are fitted around the connection part pipe 6 and the half cut cylinder bodies are integrated together by the fastening members 23, a peripheral surface 25 having no projecting part or level difference is formed. On the insides of the half cut cylinder bodies 21, 22, recessed portions 29 are formed for fitting projecting portions 8 outwardly projecting from the connection part pipe 6, and also port storage portions 30 are formed for storing the vacuum ports 11 connected to the insulated pipes 3, 4 of a superconductive cable.