  We present the results of the spectropolarimetric study of the classical
Cepheid $\eta$ Aql in 2002, 2004, 2010, and 2012. The longitudinal magnetic
field of $\eta$ Aql was found to be variable with the pulsation cycle of
7.176726 day. The amplitude, phase, and mean value of the field vary from year
to year presumably due to stellar rotation or dynamo mechanisms.
