A wireless tag communication device includes an antenna, a first maximum value acquiring unit, a second maximum value acquiring unit, a first minimum value acquiring unit, a second minimum value acquiring unit, and a polarization direction determining unit. The wireless tag communication device acquires, for each of n wireless tags provided on a sheet, a maximum value M1(k) of a received power intensity of the wireless tag when the radio wave is transmitted from the antenna to the sheet in a first polarization direction; acquires, for each of the wireless tags, a maximum value M2(k) of a received power intensity of the wireless tag when the radio wave is transmitted from the antenna in a second polarization direction that is different from the first polarization direction; acquires a minimum value m1 of M1(k); acquires a minimum value m2 of M2(k); and determines the polarization direction along which one of m1 and m2 that is not smaller is acquired as the polarization direction of the radio wave transmitted to the sheet.