•Laser cutting studies with a short focus head were performed on stainless steel plates.•The cutting experiments were performed at both constant speed and two-step speed cutting.•Cuts up to a thickness of 60 mm were achieved with a cutting capability of ∼10 mm/kW.•The kerf widths for all conditions were narrow within 2 mm. The cutting studies conducted on stainless steel plates with thicknesses of 10–60 mm using a short focus head and a high power fiber laser to evaluate application to nuclear decommissioning. The cutting performance was evaluated by determining the maximum cutting speed for each plate thickness and laser power. Both constant speed cutting and two-step speed cutting were experimentally performed. For a thickness of 10 mm, constant speed cutting had the better performance. On the other hand, two-step speed cutting achieved faster cutting for thicknesses greater than 10 mm. Even with a short focus head, cuts up to a thickness of 60 mm were achieved with a laser power of 6 kW, which corresponds to a cutting capability of ∼10 mm/kW. Kerf widths, which indicate the amount of secondary waste, were also measured in addition to maximum cutting speeds. Although there were some differences according to cutting conditions, all the kerf widths were narrow, within 2 mm.