electrodes connected to the common power terminal 15 and their c electrodes connected to scanning terminals 18 j that connect to the corresponding terminals tc j in the organic electroluminescent panel 1 thus to the scanning lines cmj the switches 12 i 13 j operate under control of the driving control unit 14 connecting their c electrodes selectively to their a electrodes and b electrodes the driving control unit 14 operates according to the data dt received at the data input terminal 19 a test signal tst received at a test control terminal 20 controls the test control unit 21 which in turn controls the test switching units 22 and 23 test switching unit 22 comprises on off switches 22 i through which the corresponding current output terminals 17 i can be selectively coupled to a test output current terminal 24 test switching unit 23 comprises on off switches 23 j through which the corresponding scanning terminals 18 j can be selectively coupled to a test input current terminal 25 next the electrical testing of the display driving circuit 10 a in the wafer state will be described as shown in fig2 the test apparatus 30 a comprises the conventional switch setting unit 31 constant.