  We report polarimetry results of a merging cluster of galaxies Abell 2256
with Karl G. Jansky Very Large Array (JVLA). We performed new observations with
JVLA at S-band (2051-3947 MHz) and X-band (8051-9947 MHz) in the C array
configuration, and detected significant polarized emissions from the radio
relic, Source A, and Source B in this cluster. We calculated the total magnetic
field strengths toward the radio relic using revised equipartition formula,
which is 1.8-5.0 microG. With dispersions of Faraday rotation measure,
magnetic-field strengths toward Sources A and B are estimated to be 0.63-1.26
microG and 0.11-0.21 microG, respectively. An extremely high degree of linear
polarization, as high as ~ 35 %, about a half of the maximum polarization, was
detected toward the radio relic, which indicates highly ordered magnetic lines
of force over the beam sizes (~ 52 kpc).The fractional polarization of the
radio relic decreases from ~ 35 % to ~ 20 % around 3 GHz as the frequency
decreases and is nearly constant between 1.37 and 3 GHz. Both analyses with
depolarization models and Faraday tomography suggest multiple depolarization
components toward the radio relic and imply the existence of turbulent magnetic
fields.
