Between 2017 and 2021, the rate of suicides by people aged 15-34 were four times higher than by those aged over 34, the agency said.
Records show 439 Thais aged 15-24 committed suicide in 2021, up from 428 a year earlier, while 956 people aged 25-34 killed themselves last year, compared to 896 in 2020.
The information was disclosed during a National Mental Health Commission meeting on Wednesday.
Department of Mental Health director-general Dr Amporn Benjaponpitak said on Thursday that the suicide rate among Thais was 7.8 per 100,000 population. She blamed suicides on higher stress caused by the impact of the Covid-19 pandemic.
The global average is nine suicides per 100,000 population, according to the United Nations.
Thailand has about 72,000 patients with psychotic disorders being treated under welfare benefits from the National Health Security Office.
A recent survey by the department on university students with mental health issues found that they looked for better understanding and the right attitude about their problems, particularly by relevant university personnel, Amporn said.
Also, they asked for close attention, increased convenience in seeking consultation, and better coordination between their university and mental health experts, who can help them.