
Police were informed of the incident at The Gallery Hotel-Condominium on Soi Jomthien 8 in Tambon Nongplue in Chon Buri's Bang Lamung district at 12.30am.
The two were identified as Maksim Kretov, 42 and Valeriya Kretov, 16.
The teenager suffered a head injury while her father broke his left leg.
Both were transferred to Pattaya Memorial Hospital.
Nattaporn Chomngarm, a security officer of the condominium, told police that he had seen the family chatting on the balcony of their second-storey room before he heard screaming and saw the two falling to the ground.
Police said they believed the two had been sitting on the balcony edge and accidentally fallen over.