The trapping of a magnetic domain wall in a Ni constriction has been observed using magnetic field sweeping-magnetic force microscopy (MFS-MFM). The Ni constriction is composed of wide and narrow tapered parts connected to each other by a constricted area with a 60 nm width. When the MFS-MFM signal, which is sensitive to the perpendicular component of a stray field, is measured around the constricted area, the signal increases at approximately -25 Oe, and is almost constant between approximately -45 and -125 Oe during an applied field swept from 500 to -500 Oe. The constant signal between approximately -45 and -125 Oe is thought to be caused by domain wall trapping around the constricted area. The width of the domain wall has been estimated to be about 260 nm around the constricted area. It is also confirmed that the domain wall spreads more toward the narrow tapered part than the wide tapered part.