A capacitive sensor device is provided, especially for determining a rotational frequency of a rotary body, for example of a washing drum and for detecting the amount and/or of the humidity grade of a laundry situated in the washing drum.The sensor device comprises a first electrode device for the irradiation of an alternating electric field, a second electrode device, into which the alternating electric field irradiated by the first electrode device can be coupled, and an evaluation circuit, which is coupled with the first electrode device and which is formed to generate the alternating electric field irradiated at the first electrode device, for detecting field-electrical interactions on at least one of the two electrode devices.The second electrode device preferably comprises a modulator for modulating the alternating electric field irradiated by the first electrode device.