Majority foreign investment in hotels, restaurants and recreational activities is subject to approval, with the exception of tourism business (travel agencies and tour operators included) in which majority foreign shareholding is prohibited as per the relevant sectoral law.
"Section 4
In this Act, “foreigner” means:
1. a natural person who is not of Thai nationality;
2. a juristic person not registered in Thailand;
3. a juristic person registered in Thailand, being of the following descriptions: 
a. being a juristic person at least one half of capital shares of which are held by persons under (1) or (2) or a juristic person in which investment has been placed by the persons under (1) or (2) in the amount at least equivalent to one half of the total capital thereof;
b. being a limited partnership or a registered ordinary partnership the managing partner or the manager of which is the person under (1);
4. a juristic person registered in Thailand at least one half of the capital shares of which are held by persons under (1), (2) or (3) or a juristic person in which investment has been placed by the persons under (1), (2) or (3) in the amount at least equivalent to one half of the total capital thereof; [...]
[...]
Section 8
Subject to section 6, section 7, section 10 and section 12:
1. no foreigner may operate such businesses stricto sensu not permissible to foreigners by special reason, as prescribed in List One;
2. no foreigner may operate such businesses related to national safety or security, businesses having impacts on arts, culture, traditions, customs and folklore handicrafts or businesses having impacts on natural resources or the environment, as prescribed in List Two, unless upon obtaining permission from the Minister with the
approval of the Council of Ministers;
3. no foreigner may operate such businesses in respect of which Thai nationals are not yet ready to compete with foreigners, as prescribed in List Three, unless upon obtaining permission from the Director-General with the approval of the Commission.
[...]
Section 13. In the case where there exist other laws which govern shareholding, partnership or investment of foreigners, permission or prohibition of the operation of certain businesses vis‐à‐vis foreigners or which prescribe rules in connection with the operation of businesses of foreigners, such laws shall prevail and the provisions of this Act shall not apply to matters insofar as they are specifically provided by other laws
[...]
Annex [...] 
List three. Businesses in respect of which Thai nationals are not ready to compete with foreigners  [...] 
(17) Hotel business, with the exception of the hotel management service
(18) Guided touring
(19) Sale of food and beverages [...]"((Foreign Business Act, B.E. 2542 (1999))
------------------------------
"[...] Section 4. In this Act: “Tourism business” means a business relating to guiding tourists for touring or for other purposes of traveling by providing either one or several services or conveniences such as lodging, food, guide, or any other services as prescribed in the Ministerial Regulation.
[...]
CHAPTER I - Tourism Business
Section 15. Any person who intends to operate a tourism business shall apply for a tourism business licence with the registrar. An application of licence, issuance of licence, and issuance of duplicate copy of licence shall be in accordance with the criteria and procedure prescribed in the Ministerial Regulation.
Section 16. A natural person who applies for a tourism business licence shall: (1) have qualifications as follows: (A) being not less than twenty years of age on an application date of tourism business licence; (B) being of Thai nationality; (C) being domiciled or resided in the Kingdom of Thailand [...]
Section 17. A juristic person who applies for a tourism business licence shall: (1) have qualifications as follows; (A) being the juristic person under Thai law whose objective is to operate business concerning with tourism. If such juristic person is a registered partnership, an unlimited liability partner shall have Thai nationality. If such juristic person is a limited company or public limited company, no less than fifty one percent of a company’s capital shall belong to a natural person who has Thai nationality and more than half of such company’s directors shall have Thai nationality; (B) the director or a person who has the power to act on behalf of the juristic person shall have qualifications and not be under the prohibitions under section 16; [...]"(Tourism Business and Guide Act, B.E. 2551 (2008))"
Foreign Business Act, B.E. 2542 (1999).
Tourism Business and Guide Act, B.E. 2551 (2008)
[<a href="https://investmentpolicy.unctad.org/investment-laws/laws/40/thailand-foreign-business-act">Act</a>],[<a href="http://web.krisdika.go.th/data/outsitedata/outsite21/file/TOURISM_BUSINESS_AND_GUIDE_ACT_B.E._2551.pdf ">Act</a>]