Visa on arrival
Any foreigner who arrives Bangladesh without Visa can avail Visa On Arrival with very few exceptions. Visa Cell of Immigration Police at Hazrat Shahjalal International Airport issues Visa on arrival to the passengers upon government directive. The Visa cell is located at the ground floor of the terminal building (at the right when you come down through arrival escalator/stair).
As per government order Visa Cell, Shahjalal International Airport is authorized to issue the visa on arrival for those who has arrived in Bangladesh without visa.To collect a visa on arrival, the passenger will have to pay a set fee which is determined by the Bangladesh Government. The amount is around 50 USD (plus or minus). One more thing, foreigners are required to complete registration process upon arrival in Bangladesh. If you are interested more, then you can can have a look at the visa policies of Bangladesh.