The seasonal abundance of Haemaphysalis longicornis Neumann and H. flava Neumann (Acari: Ixodidae) was monitored from 2015 through 2017 in Gyeonggi-do, South Korea. The hard ticks were surveyed monthly using CO₂ bait traps from April to November and flagging from July to September in a coniferous forest, a deciduous forest, shrubs, and a grassland vegetation types. Haemaphysalis longicornis and H. flava were most abundant in the grassland and shrubs, which yielded over 50% of the total number of ticks in all 3 yr. Furthermore, H. longicornis comprised up to 90% of the ticks collected. Generally, peaks of nymph, adult, and larva numbers were observed from April to June, from June to July, and from August to September, respectively. Half of the ticks were pooled and tested for the presence of the SFTS virus with negative results.