"The Swiss franc is still highly valued but it should depreciate further in the future," Jean-Pierre Danthine said in an address at Zurich University.
The SNB will continue to enforce the minimum rate by remaining prepared to buy unlimited quantities of foreign currencies, Danthine said, echoing a central bank statement released at the start of the year.
The franc, considered a safe haven in times of financial turbulence, posted a sharp gain in value last year, going from 1.23 per euro at the beginning of July to less than 1.05 a month later.
It has remained near 1.20 since a central bank intervention in September.
The SNB was dealt a blow with the loss of earlier this month of its head Philipp Hildebrand, who stepped down following an outcry over foreign currency exchanges made by his wife.
Danthine said he "deeply regretted" Hildebrand's resignation.