Zazenkai, also known as Zen meditation or Zen Mindfulness, is held in Japan for the general public, usually with time, place and procedures set by a Buddhist Zen Temple. With the emergence of the Internet and new media, several Zen Temples have started to hold Zazenkai by utilizing these media technologies including online live streaming. This new type of Zazenkai is known as Internet Zazenkai. Compared with traditional Zazenkai that are held at a certain time and place, the application of new media enables Internet Zazenkai to go beyond the spatial and temporal limits of nature, where Zen practitioners in different global locations participate together using webcam. Individuals spatially separated from each other could share the same time and space of Zazenkai on the Internet. While the new media technologies open up new opportunities for Zazenkai, they also invite examinations into religious meanings of time and space for Zen practitioners. This paper is based on the study and examination of Internet Zazenkai regularly held by Treeleaf Zendo, a Soto Zen temple in Tsukuba. Its homepage Treeleaf.org is a virtual space where live streaming of Zazenkai is provided, its recorded videos are kept, web podcast of lectures and talks are heard, and so on. By analyzing the techno-ritual phenomenon, this paper attempts to analyze the role of Zen masters and participants in the process of Internet Zazenkai and to examine the differences and similarities between traditional Zazenkai and Internet Zazenkai. This paper will shed new light on the influence of new media upon religious and ritual space in modern society.