A sounding rocket S-310-18 was launched at 11 : 00 LT on the 26th, January 1988 to find heat sources which may cause the anomalous elevation of the E region electron temperature over Uchinoura. We measured plasma and electric field disturbances by a fixed biased Langmuir probe (PWN) and a pair of double probes (AEF), respectively, onboard the rocket. The PWN measured abrupt decrease of the DC current and increase of the AC current (5-160Hz component) in the altitude range of 94-130km during the ascending path where the AEF also measured increase of the AC electric field (5-160Hz component). It is revealed from comparative analysis of the PWN and the AEF data that the potential of the rocket dropped for a few volts probably accompanied by low frequency variations in that altitude range. An other group (TEL) measured an elevated electron temperature in the same altitude range. Coincident occurrence of these phenomena suggests common cause.