Ralph "Eugene" Todd, 31, of Menlo Park, was taken into custody on Dec. 19 for allegedly performing lewd and lascivious acts on a child, police said.
Todd had taught at the Kim's Tae Kwon Do Academy in Woodside Plaza for 12 years, according to police.
Detectives are attempting to gain more information to determine if there are additional victims or witnesses.
Police Lt. Sean Hart said investigators have spoken with all of current students at the academy, but are looking into whether there are past students who may have been abused.
Todd is out of custody on bail, Hart said.
Anyone with information regarding Todd is asked to contact Redwood City police Detective Megan Boyajian at (650) 780-7138.