The time series of the interplanetary and Earth's magnetotail magnetic
fields are analyzed. The data subsets taken by the IMP 8 spacecraft o
utside and inside of the Earth's magnetosphere show clearly the fracta
l properties: their ''box dimensions'' are found to be close to 1.7 an
d 1.5 respectively. It is shown that data gaps have a little effect on
the results. The magnetic field increment distributions are found to
be non-Gaussian, but self-affine.