The suspect, identified by police as Apichart Thawibun, was also found in possession of methamphetamine at the time of his arrest, Thalang Police reported.
The case came to light last Sunday (Nov 17) when the children’s mother, 28, reported the abuse to Thalang Police Station.
She brought her children to the station, showing officers the bruises and other injuries on their faces and bodies.
The children had reportedly been beaten by their stepfather, who allegedly slapped and punched them, and struck them with a shoe.
The assault occurred two days earlier, on Nov 15, at a residence in Tambon Srisoonthorn, the mother told police.
Police promptly arranged for the children to receive medical attention at Thalang Hospital while launching an investigation into the matter.
On Thursday evening (Nov 21), police, led by Pol Lt Col Suchart Luecha and other officers, apprehended Apichart at his residence in Srisoonthorn.
While making the arrest, police discovered two methamphetamine pills in his possession.
Apichart confessed to both using the drugs and assaulting his stepchildren, claiming it was a result of a “momentary lapse of reason”.
Apichart was taken to Thalang Police Station to face charges of drug possession and assault.
Authorities are continuing their investigation and legal proceedings.