<p>An increase in the sika deer (<i>Cervus nippon</i>) population may result in a rise in the number of patients with tick-borne diseases in Japan, due to the increased questing (host-seeking) tick density. Although previous studies have examined the impact of sika deer on the questing tick density in specific regions, regional differences among tick species remain understudied. To clarify the general and regional effects of sika deer presence on tick species density, we analyzed published and field data using generalized linear mixed models. Regression coefficients for sika deer presence relative to the densities of questing <i>Haemaphysalis kitaokai</i>, <i>Haemaphysalis longicornis</i>, and <i>Haemaphysalis megaspinosa</i> were positive in most prefectures, suggesting that deer presence is associated with increased densities of these species. In contrast, coefficients for <i>Haemaphysalis flava</i> varied by region, showing no significant, positive, or negative associations depending on location. For <i>Ixodes ovatus</i>, the coefficients were not significant in Niigata Prefecture but were positive in Hokkaido Prefecture, indicating regional variation These findings suggest that the impact of sika deer on the increased density of <i>H. flava</i> and <i>I. ovatus</i> may vary by region. In addition, the risk of human infection caused by tick-borne pathogens transmitted by tick species positively affected by the presence of sika deer may increase due to the expansion of sika deer distribution. In the future, the impact of sika deer on tick density should be considered in various management decisions such as agricultural, environmental and public health departments.</p>