Buchanania arborescens (Bl.) Bl., Mus. Bot. 1: 183 (1850) (syn: Buchanania angustifolia Benth.; Buchanania arborescens F.Muell.; Buchanania attopeuensis (Pierre) Tardieu; Buchanania bancana Miq.; Buchanania florida A.Gray; Buchanania glaberrima Ridl.; Buchanania intermedia Wight; Buchanania longifolia Blume Buchanania longifolia Span.; Buchanania lucida Blume; Buchanania monticola Kaneh. & Hatus.; Buchanania muelleri Engl.; Buchanania nabirensis Kaneh. & Hatus.; Buchanania novohibernica Lauterb.; Buchanania palembanica Blume; Buchanania papuana C.T.White; Buchanania petiolaris Miq.; Buchanania platyphylla Merr.; Buchanania polybotrya Miq.; Buchanania pseudoflorida G.Perkins; Buchanania scandens Lauterb.; Buchanania solomonensis Merr. & L.M.Perry; Buchanania subobovata Griff.; Buchanania versteeghii Merr. & L.M.Perry; Coniogeton arborescens Blume; Lauro-cerasus laurifolia (Decne.) M.Roem.; Prunus laurifolia Decne.);
S. Taiwan, Tropical Asia to N. Australia: Andaman Is., Bismarck Archipelago, Borneo, Cambodia, Jawa, Laos, Lesser Sunda Is., Malaya, Maluku, Myanmar, New Guinea, Northern Territory, Philippines, Queensland, Solomon Is., Sulawesi, Sumatera, Taiwan, Thailand, Vietnam as per POWO;


May be Anacardiaceae: A tree ca 8 m tall, ca 20 cm diameter. Fruits ca 15 mm diameter. ID is requested. Thank you.

Just making a guess.. how about Mangifera caesia Jack

It seems to be matching much with your plant, provided the matuired fruits attain a bigger size. As per my observation on your plant, the fruits are very tender and yet to gain their size.

Thank you for your answer. The inflorescence is not really terminal, it is subterminal, the seeds are very hard, the carpel is very thin. I saw this tree some months ago with the same fruit size. I think this is not M. caesia. I am not sure. 

Fruits look smaller !

After observing for a long time, I guess that this may be Buchanania arborescens?  Could you validate please.