Atris Hussein was arrested in Bangkok in January and police later found a large amount of chemicals that can be used to make a bomb at an address he rented.
According to the charges, Hussein and some unidentified accomplices had packed more than six tonnes of ammonium nitrate into bags.
"He pleaded not guilty on this charge," said lawyer Withaya Buranasil, who met his client for the first time on Wednesday before his appearance at a Bangkok court.
Hussein will next appear for a pre-trial hearing in May, Withaya said, adding that he did not plan to seek bail at present.
If found guilty, he could face five years in jail or a 50,000 baht ($1,700) fine.
Ammonium nitrate is commonly used in agriculture, but mixed with other substances can make a bomb and possession of the chemical requires a permit in Thailand.
Prior to his arrest, the United States had warned of a "serious" threat of a terrorist attack on tourist areas in Bangkok.
The country has been further shaken by a string of botched blasts in the capital on February 14 in an alleged plot to kill Israeli diplomats.
Thai police are holding two Iranians, one of whom was badly hurt as he hurled a bomb at police while fleeing.
Another suspect was detained in Malaysia, while arrest warrants have been issued for two more Iranians believed to have left the country.
Israel has blamed Iran over the Bangkok blasts, as well as attacks on Israeli embassy staff in India and Georgia a day earlier.