This study investigates the properties of particles in Japanese from a pragmatic viewpoint. The main target of analysis is "wa" and "ga", which are regarded as a topic and nominative marker respectively. The research is based on the pragmatic theory proposed by Levinson (2000). This dissertation consists of three parts as follows. The first part investigates the contrastive usage of "wa/ha" from a historical perspective. I elicited examples of "wa/ha", "ga" and "no" from five Classical literary works and two Modern works. The text data showed that, in Late Old/Middle Japanese, the "ha"-marking worked as the emphatic marker, but not used for maintaining the topic continuity, while the "ga" as the nominative marker was scarce and with a limited distribution. I claim that the contrastive property of "ha" in Classical Japanese was provided by the M-implicature. In Early Modern Japanese, the two works showed different result. Saikaku Shokokubanashi is regarded as a middle step toward Modern Japanese from Middle Japanese while Oku no Hosomichi retained the trend of the Late Old/Middle Japanese. The second part argues that the contrastive property of "wa" is given by the non-specificity implicature based on Grice's Maxim of Quantity. I proposed that the two particles form the scalar terms particles form the scalar terms, ["ga"."wa"], which means that the "wa" is informationally weaker than the "ga". The hearer pragmatically infers that if a speaker knew that an NP was a specific item in the discourse, s/he would use "ga", but actually s/he did not, and used "wa" instead, where s/he eliminates the possibility that the NP is the one and only one item in the discourse. In the case where "wa" appears at the position incompatible with "ga", the implicature is given by M-implicature. Experiment was performed to test the hypothesis. A free association task of writing a sentence following a "wa"-altered perceptual judgment sentence ("ga"-marked by default) and experiential judgment sentence ("wa"-marked by default) was given. The participants wrote the sentences in the way that they fulfill the contrastive framework more frequently after the "wa"-altered perceptual judgment sentences than after the experiential judgment sentences. The result exhibited the effect of the stronger implicature in the "wa"-altered perceptual judgment sentence. The third part examines the effect of particles attached to the quantifier terms to scalar implicatures in Japanese. A neo-Gricean view on scalar implicatures argues that quantifiers represent the lower bound in a default, i.e., "at least" interpretation, and pragmatics provides them with upper bound scalar implicatures. I hypothesized the particle "ga" attached to quantifiers strengthens the implicatures of the sentence, while the particle "wa" weakens them and provides the "at least" interpretation. Zero marking cancels both effects. "O" has the similar but not so strong effect as "ga". To prove this, two Experiments were performed based on the concept in Papafragou & Musolino (2003). A truth value judgment task was given to test sentences involving weaker terms, "eight", "some", and "most", marked by the particle "ga", "wa", "o", and zero under the condition involving the strong term "all ten." In Experiment I the effect of the particles was tested within-group. In Experiment II their effect were tested between distinct groups. The number term showed lower ratings of truth value judgment with "ga" than it did with "wa" in both experiments. In contrast, "most" showed higher ratings with "ga" than it did with "wa" only in Experiment I. The particles attached to "some" hardly provide any effect. The observed regularities for the number term are explained by the exclusive function of "ga" and the contrastive usage of "wa". The result for "most" is also explained by the proposal by Ariel (2004). [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited withoutpermission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]