An improved error box of GRB 970815 has been reported very recently (Smith et al.1999). This error box is consistent with the decaying X-ray source detected by ROSAT, which strongly supports the source as the GRB X-ray afterglow. We report a re-analysis of the follow up observations performed in 1997 containing the improved RXTE error box. No variable optical/IR source has been found neither within the entire RXTE error box nor within the ROSAT and ASCA X-ray circles. Upper limits for any transient object are K'>=18 (Aug 17 1997), B>=21.5, R>=22 (20 Aug 1997), B>=22.5 and R>=23 (23 Aug 1997). Also we report additional BVRI optical observations performed in 1999 of the ROSAT X-ray source aimed to detect the host galaxy of GRB 970815. .