江戸幕府の約260年という長い歴史は、決して平穏無事なだけではなかった。幕府はその存続期間中、財政の悪化、武士の綱紀の緩み、社会矛盾の噴出といった様々な課題に直面し、そのたびに「改革」という名のメスを入れ、体制の立て直しを図ろうとしてきた。その中でも特に規模が大きく、後世に大きな影響を与えたのが、享保の改革（きょうほうのかいかく）、寛政の改革（かんせいのかいかく）、そして天保の改革（てんぽうのかいかく）の三つだ。これらを総称して「三大改革」と呼ぶ。
このページでは、これら三大改革が、それぞれどのような時代背景のもとで、誰によって、どのような理念で進められ、具体的にどんな政策が実行されたのか。そして、その結果としてどのような成果を上げ、またどのような限界に直面したのかを、徹底的に比較分析していく。なぜ改革は繰り返されたのか？ なぜ根本的な解決には至らなかったのか？ これらの問いを通じて、江戸幕府の政治が抱えていた構造的な課題と、その対応の苦闘、そして歴史の必然とも言える変化のうねりを感じ取ってほしい。東大入試では、これらの改革の比較や、特定の改革が持つ歴史的意義を深く論じさせる問題が頻出するから、ここでしっかりとその本質を掴もう。
【学術的豆知識】「改革」という言葉の多義性
僕たちが「改革」というと、何か新しい、より良い方向へ物事を大きく変えるというポジティブなイメージを持つことが多いかもしれない。しかし、江戸時代の「改革」は、必ずしも「革新」や「進歩」を意味したわけではないんだ。特に享保の改革や寛政の改革が「祖法への復帰」や「原点回帰」をスローガンに掲げたように、むしろ「古き良き時代（とされた過去）への回帰」を目指す、ある種保守的な性格を持っていた場合も多い。これは、改革の指導者たちが、当時の社会変動を「風紀の乱れ」や「秩序の崩壊」と捉え、それを「正しい状態」に戻そうとしたからだ。こうした「改革」観の違いを理解することも、歴史を深く読み解く上で面白い視点だね。
(Click to listen) When we hear "reform," we often associate it with positive connotations of significant change towards something new and better. However, "reforms" during the Edo period did not always signify "innovation" or "progress." As seen in the Kyoho and Kansei Reforms, which aimed for a "return to ancestral laws" or "back to basics," they often had a somewhat conservative character, aspiring to revert to a "golden age of the past." This was because reform leaders perceived contemporary social changes as "moral decay" or "breakdown of order" and sought to restore what they considered the "correct state." Understanding these different perspectives on "reform" is an interesting viewpoint for deeply interpreting history.
This Page's Summary in English (Click to expand and listen to paragraphs)
This page provides a comparative analysis of the "Three Great Reforms" of the Edo period: the Kyōhō (1716-45), Kansei (1787-93), and Tenpō (1841-43) Reforms. These were major attempts by the Shogunate to address accumulating problems such as fiscal deficits, samurai indiscipline, and social unrest.
The Kyōhō Reforms, led by Shogun Tokugawa Yoshimune, aimed at fiscal reconstruction and moral rededication, inspired by the early days of the Shogunate. Key policies included austerity, land reclamation, tax reforms (jōmen system), and codification of laws (Kujikata Osadamegaki). It achieved some fiscal improvement but also increased peasant burdens.
The Kansei Reforms, led by Rōjū Matsudaira Sadanobu, sought to emulate Yoshimune's reforms, responding to the perceived corruption of the Tanuma era and social anxiety after the Tenmei Famine. Policies included strict frugality, encouragement of agriculture (Kyūri Kinōrei), debt cancellation for retainers (Kienrei), and ideological control (Kansei Edict against Heterodox Studies). It brought temporary fiscal relief but was criticized for excessive strictness and stifling economic vitality.
The Tenpō Reforms, led by Rōjū Mizuno Tadakuni, were a response to severe famine, social unrest (e.g., Ōshio Heihachirō's Rebellion), and growing external threats (e.g., the Opium War). It attempted radical measures like dissolving merchant guilds (kabunakama) and land consolidation (Agechirei, which failed), but largely failed due to widespread opposition and economic disruption.
Common goals of these reforms included fiscal rebuilding and restoring samurai discipline, often with an agrarian fundamentalist bias. However, they differed in leadership, specific policies, and outcomes. The reforms were repeated because they failed to address the fundamental structural contradictions of the Bakuhan system, such as the mismatch between the rice-based stipend system and the developing monetary economy. Ultimately, these reforms were largely palliative within the existing framework, unable to cope with profound socio-economic changes, thus foreshadowing the Bakumatsu upheavals.