To provide an ultrasonic probe and an attachment that save labor in an ultrasonic diagnosis involving biological electric signal measurement.

The ultrasonic probe 100 has an electrode in a subject abutting part 102, and a signal wire for the electrode is inside a signal cable 104 of the ultrasonic probe. The signal wire may be brought out of the cable, or may be detachable from the electrode. The electrode is for the ECG (electrocardiogram). The electrode may be mounted on the attachment for the ultrasonic probe.