A cab for a construction machine, the cab comprising: a floor for a driving operation; a floor plate; a footrest; a floor mat including a planar portion and being provided on the floor on the floor plate, wherein the floor mat is provided with the footrest; an operator's seat for an operator to be seated; and a trainer's seat for a trainer to be seated, the operator's seat and the trainer's seat being provided in parallel to each other on the floor, the footrest comprising: an operator's footrest; and a trainer's footrest, the floor mat is characterized by comprising: a first projection projecting from the planar portion of the floor for the operator's footrest, a first placement surface configured to be used for a foot of the seated operator, the first placement surface being provided on the first projection of the operator's footrest facing the operator's seat and being formed to be an inclined surface that is inclined forward in an upper direction, a second projection projecting from the planar portion of the floor for the trainer's footrest, and a second placement surface configured to be used for a foot of the seated trainer, the second placement surface being provided on the second projection of the trainer's footrest facing the trainer's seat and being formed to be an inclined surface that is inclined forward in the upper direction, the operator's footrest and the trainer's footrest are adjacent to or integrated with each other without a gap, and the first placement surface of the operator's footrest projects beyond the second placement surface of the trainer's footrest. a floor for a driving operation; a floor plate; a footrest; a floor mat including a planar portion and being provided on the floor on the floor plate, wherein the floor mat is provided with the footrest; an operator's seat for an operator to be seated; and a trainer's seat for a trainer to be seated, the operator's seat and the trainer's seat being provided in parallel to each other on the floor, the footrest comprising: an operator's footrest; and a trainer's footrest, the floor mat is characterized by comprising: a first projection projecting from the planar portion of the floor for the operator's footrest, a first placement surface configured to be used for a foot of the seated operator, the first placement surface being provided on the first projection of the operator's footrest facing the operator's seat and being formed to be an inclined surface that is inclined forward in an upper direction, a second projection projecting from the planar portion of the floor for the trainer's footrest, and a second placement surface configured to be used for a foot of the seated trainer, the second placement surface being provided on the second projection of the trainer's footrest facing the trainer's seat and being formed to be an inclined surface that is inclined forward in the upper direction, the operator's footrest and the trainer's footrest are adjacent to or integrated with each other without a gap, and the first placement surface of the operator's footrest projects beyond the second placement surface of the trainer's footrest. an operator's footrest; and a trainer's footrest, a first projection projecting from the planar portion of the floor for the operator's footrest, a first placement surface configured to be used for a foot of the seated operator, the first placement surface being provided on the first projection of the operator's footrest facing the operator's seat and being formed to be an inclined surface that is inclined forward in an upper direction, a second projection projecting from the planar portion of the floor for the trainer's footrest, and a second placement surface configured to be used for a foot of the seated trainer, the second placement surface being provided on the second projection of the trainer's footrest facing the trainer's seat and being formed to be an inclined surface that is inclined forward in the upper direction, the operator's footrest and the trainer's footrest are adjacent to or integrated with each other without a gap, and the first placement surface of the operator's footrest projects beyond the second placement surface of the trainer's footrest.