A piezoelectric actuator unit including: a plurality of sets (A,B,C), each set (A,B,C) including: a plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3), each configured to supply an electrical signal to a corresponding one of the plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), and a common electrode (Ca,Cb,Cc) that is configured to supply a common electrical signal to each of the plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), wherein: the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) and the common electrode (Ca,Cb,Cc) of each set (A,B,C) are electrically independent of one another, characterised in that piezoelectric actuator unit is configured so that: a) a plurality of the common electrodes (Ca, Cb, Cc) are connected to each other by an inter-common electrode resistance in at least one place, and an electric resistivity of the inter-common electrode resistance is higher than an electric resistivity of the common electrodes (Ca, Cb, Cc) and is lower than an electric resistivity of a member forming a face on which the common electrodes (Ca, Cb, Cc) are formed; and/or b) a plurality of the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) are connected to each other by an inter-individual electrode resistance in at least one place, and an electric resistivity of the inter-individual electrode resistance is higher than an electric resistivity of the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) and is lower than an electric resistivity of a member forming a face on which the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) are formed. a plurality of sets (A,B,C), each set (A,B,C) including: a plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3), each configured to supply an electrical signal to a corresponding one of the plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), and a common electrode (Ca,Cb,Cc) that is configured to supply a common electrical signal to each of the plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), wherein: a plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3), each configured to supply an electrical signal to a corresponding one of the plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), and a common electrode (Ca,Cb,Cc) that is configured to supply a common electrical signal to each of the plurality of piezoelectric elements (a1, a2, a3, b1, b2, b3, c1, c2, c3), wherein: the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) and the common electrode (Ca,Cb,Cc) of each set (A,B,C) are electrically independent of one another, characterised in that piezoelectric actuator unit is configured so that: a) a plurality of the common electrodes (Ca, Cb, Cc) are connected to each other by an inter-common electrode resistance in at least one place, and an electric resistivity of the inter-common electrode resistance is higher than an electric resistivity of the common electrodes (Ca, Cb, Cc) and is lower than an electric resistivity of a member forming a face on which the common electrodes (Ca, Cb, Cc) are formed; and/or b) a plurality of the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) are connected to each other by an inter-individual electrode resistance in at least one place, and an electric resistivity of the inter-individual electrode resistance is higher than an electric resistivity of the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) and is lower than an electric resistivity of a member forming a face on which the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) are formed. a) a plurality of the common electrodes (Ca, Cb, Cc) are connected to each other by an inter-common electrode resistance in at least one place, and an electric resistivity of the inter-common electrode resistance is higher than an electric resistivity of the common electrodes (Ca, Cb, Cc) and is lower than an electric resistivity of a member forming a face on which the common electrodes (Ca, Cb, Cc) are formed; and/or b) a plurality of the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) are connected to each other by an inter-individual electrode resistance in at least one place, and an electric resistivity of the inter-individual electrode resistance is higher than an electric resistivity of the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) and is lower than an electric resistivity of a member forming a face on which the individual electrodes (Pa1, Pa2, Pa3, Pb1, Pb2, Pb3, Pc1, Pc2, Pc3) are formed.