Probe (1) for deep electrical neurostimulation, and more specifically for deep brain electrostimulation, comprising: a tubular body (10) of biocompatible material with a lateral wall (11) defining a lumen (12) and a closed anterior end (13), said tubular body (11) can be introduced for at least a part of its length inside a patient's body for reaching a region to be stimulated; wherein it also comprises: a plurality of electrically insulating arms (32) each bearing at least one electrode (40) and being able to pass from a first position in which they are housed inside of said tubular body (11) to a second position in which they project radially from this latter and inversely; and means (20 and 50) for making said arms (32) pass from said first position to said second position and inversely.