TOKYO, Oct 27 (Reuters) - Japan Post Insurance is getting wary of the risk of the yen's rebound after its fall to a four-year low against the dollar and is cautious about buying foreign bonds without currency hedge, a top investment planning official said on Wednesday.

"We are cautious on unhedged foreign bonds. The yen has already weakened considerably. We are not increasing their holdings when the yen is at current levels," Hiroyuki Nomura, head of investment planning, told reporters in a news conference. (Reporting by Hideyuki Sano)