Hundreds of mourners gathered in Samut Prakan province on Wednesday for the funeral of Amphon Tangnoppakul, also known as "Uncle SMS".
He died less than six months into a 20-year prison sentence for sending four text messages that were deemed insulting to the Thai monarchy.
Tangnoppakul's death has shone a light on the country's strict lese majeste laws, legal stipulations which criminalise the violation of the royal family and which were designed to prevent criticism of them.
Yingluck Shinawtra, Thai prime minister, has admitted to Al Jazeera that the law is sometimes misused, while a growing portion of the public is now calling for it to be changed.
Al Jazeera's Wayne Hay reports from Samut Prakan.