The Hello Kitty cartoon character is known across Asia
The armband is large, bright pink and has a Hello Kitty motif with two hearts embroidered on it.
From today, officers who are late, park in the wrong place or commit other minor transgressions will have to wear it for several days.
The armband is designed to shame the wearer, police officials said.
"This is to help build discipline. We should not let small offences go unnoticed," Police Colonel Pongpat Chayapan told Reuters news agency.
"Guilty officers will be made to wear the armbands in the office for a few days, with instructions not to disclose their offences. Let people guess what they have done," he said.