An electric stimulator for applying an electric signal to the body of a patient through electrodes (H, S) to stimulate the brain of the patient; comprising: main electrodes adapted to be stuck to a particular site in the body of a patient extending from the neck part to the head tip part so as to apply stimulation to the brain without passage through the brain stem; wherein: the electric signal to be applied to the main electrodes is set for a weak electric current stimulating the brain to flow through the body of the patient; wherein said weak electric current has a frequency of from 10 to 80 pulses per second and an electric current value of from 10 μA to 100 μA; the weak electric current is applied by repeating a predetermined cycle; the predetermined cycle comprises a first state and a second state, the first state being a state in which the application of the weak electric current is continued for a fixed period of time and the second state being a state in which the application of the weak electric current is ceased after the first state for a period of time equal to or longer than the fixed period of time for the first state; the application of the weak electric current is applied in the first state to gradually increase the weak electric current toward a predetermined electric current value and then maintain the predetermined electric current value for a period of time longer than the period of time during which the weak electric current is increased gradually; and the timing at which the electric signal is applied to plural numbers of the main electrodes is set to shift gradually from synchronization and re-synchronize in a constant cycle. main electrodes adapted to be stuck to a particular site in the body of a patient extending from the neck part to the head tip part so as to apply stimulation to the brain without passage through the brain stem; wherein: the electric signal to be applied to the main electrodes is set for a weak electric current stimulating the brain to flow through the body of the patient; wherein said weak electric current has a frequency of from 10 to 80 pulses per second and an electric current value of from 10 μA to 100 μA; the weak electric current is applied by repeating a predetermined cycle; the predetermined cycle comprises a first state and a second state, the first state being a state in which the application of the weak electric current is continued for a fixed period of time and the second state being a state in which the application of the weak electric current is ceased after the first state for a period of time equal to or longer than the fixed period of time for the first state; the application of the weak electric current is applied in the first state to gradually increase the weak electric current toward a predetermined electric current value and then maintain the predetermined electric current value for a period of time longer than the period of time during which the weak electric current is increased gradually; and the timing at which the electric signal is applied to plural numbers of the main electrodes is set to shift gradually from synchronization and re-synchronize in a constant cycle. the electric signal to be applied to the main electrodes is set for a weak electric current stimulating the brain to flow through the body of the patient; wherein said weak electric current has a frequency of from 10 to 80 pulses per second and an electric current value of from 10 μA to 100 μA; the weak electric current is applied by repeating a predetermined cycle; the predetermined cycle comprises a first state and a second state, the first state being a state in which the application of the weak electric current is continued for a fixed period of time and the second state being a state in which the application of the weak electric current is ceased after the first state for a period of time equal to or longer than the fixed period of time for the first state; the application of the weak electric current is applied in the first state to gradually increase the weak electric current toward a predetermined electric current value and then maintain the predetermined electric current value for a period of time longer than the period of time during which the weak electric current is increased gradually; and the timing at which the electric signal is applied to plural numbers of the main electrodes is set to shift gradually from synchronization and re-synchronize in a constant cycle.