To enable a cylindrical body with an after-treatment device built in to be stably mounted on a work bench or the like, and to facilitate a cleaning work or the like of the after-treatment device.

An upstream cylindrical body 22 and downstream cylindrical body 28 are fixedly mounted in an emission control device supporting bracket 16 by employing supporting legs 26, 31. A cylindrical part 33A of a cylindrical body 32 (a cylindrical case 33) for a filter keeps a placing leg 35 on the undersurface side and a handle part 37 on the top surface side of the cylindrical part 33A. When pulling the cylindrical body 32 for a filter out of between the upstream cylindrical body 22 and downstream cylindrical body 28, only the cylindrical body 32 for a filter is removed with the handle part 37 grasped and lifted by removing each bolt 38 and nut 39. When the removed cylindrical body 32 for a filter is mounted on a work bench or the like, the cylindrical body 32 for a filter is kept in a stably mounted state on the work bench by grounding the placing leg 35 on the work bench.