Abstract: A nailer for suppressing misfire while keeping operability. In a first mode, a control circuit drives a drive source when a second ON determination is made and a first ON determination is made in a state where a second operation unit is maintained at a second ON position, and when the drive source is driven and then a second OFF determination is made in a state where a first operation unit is maintained at a first ON position, the control circuit does not drive the drive source again unless returning to the initial state. In a second mode, the control circuit drives the drive source when the first ON determination is made and the second ON determination is made in a state where the first operation unit is maintained at the first ON position. A second OFF determination time in the second mode is longer than in the first mode.