Ticks are important vectors of infectious diseases, transmitting viral, bacterial, and protozoan pathogens to humans. Among tick-borne diseases, severe fever thrombocytopenia syndrome (SFTS), which was first discovered in China in 2009, has been designated as a class 3 legal infectious disease in the Republic of Korea (ROK), where it was first reported in 2013. The number of patients with SFTS has continued to increase since the first report. The tick population in the country was monitored to prevent tick-borne diseases. The Division of Vectors and Parasitic Diseases of the Korea Disease Control and Prevention Agency operates a climate change vector surveillance center. The survey was conducted in copses, grasslands, graves, and mountain roads (a total of four environments) in 32 regions from April to November of 2023. In this survey, 110,624 ticks were collected, and three genera and five species were identified. The dominant species among the classified ticks was Haemaphysalis longicornis (except for larvae). In terms of the environment, most of the ticks were collected from grasslands (53,348 ticks, 48.2%), followed by graves (24,904 ticks, 22.5%), copses (18,241 ticks, 16.5%), and mountain roads (14,131 ticks, 12.8%). The tick index (trap index; number of individuals/traps/days) in 2023 decreased by 9.8% and 32.8% compared with the percentage and average percentage in 2022 and for 2018-2022, respectively. Because tick-borne infectious diseases are steadily increasing in the ROK, annual surveillance of changes in tick populations due to climatic and geographical factors is essential for public health. The occurrence of ticks in 2023 decreased by 9.8% compared with that the previous year. However, there is a high risk that ticks and tick-borne diseases will increase owing to climate change; therefore, surveillance for ticks must be conducted continuously.