[Objective] This study explores the concept of “neighbor” in the Greek New Testament by examining the usage of περίοικος, πλησίον, and γείτων, and considers how the teachings on love for one’s neighbor can be extended to an ecological perspective. [Contents] To investigate the ecological implications of the New Testament's teaching on neighborly love, the study develops its argument in three stages. First, it analyzes the occurrences of “neighbor” in the Greek New Testament and organizes the concept. Second, it examines the expansion of neighborly love, which encompasses all others, with a particular focus on γείτων in the New Testament and ן in the Old Testament, to consider how the concept extends to include the earth. Third, the study interprets Genesis 2:15, where humanity is instructed to “till and keep” the land, providing a biblical basis for extending neighborly love to the ecosystem. [Conclusions] The findings suggest that the concept of “neighbor” in the New Testament extends beyond proximity to include all entities in need, including the earth. The terms γείτω- ν, derived from γῆ(earth), and ן meaning “dweller,” imply that the earth itself can be regarded as a neighbor. Through the Hebrew verbs עבד (“to till”) and שׁמר (“to keep”) in Genesis 2:15, the study highlights humanity's responsibility toward the land and all creatures, underscoring the biblical foundation for expanding neighborly love to the ecological domain.