The cab of the construction machine comprising a pair of side panels 1, 2, a front panel 3 with a window fitting part 13 formed at an upper position, and a ceiling panel with a ceiling panel connection part 14 formed adjacent to the window fitting part 13 of the front panel 3 extends to the indoor side of the cab along the ceiling panel connection part 14, and has a cylindrical connection body 33to connect a pair of side panels. The cylindrical connection body 33 is joined with each side panel at an end face in the extending direction of the cylindrical connection body 33, and the front panel 3 is joined with the cylindrical connection body 33 in a vicinity of an end of the extending direction of the cylindrical connection body.