宗教改革日是基督教新教的一个宗教节日，在每年10月31日庆祝，纪念马丁路德开启的基督教宗教改革，起因于路德于1517年10月31日在德意志的威登堡提出了《九十五条论纲》，是新教运动的开端。故特别在信义宗和归正宗教会中被纪念。

宗教改革日在以下地方是公共假期：斯洛文尼亚（宗教改革对其文化发展贡献甚大，尽管斯洛文尼亚人大部分是天主教徒）和德国的勃兰登堡州、梅克伦堡-前波美拉尼亚、萨克森州、萨克森-安哈尔特州和图林根州。

Reformation Day is a religious holiday celebrated on October 31, alongside All Hallows' Eve, in remembrance of the Reformation. It is celebrated among various Protestants, especially by Lutheran and Reformed church communities.

It is a civic holiday in the German states of Brandenburg, Mecklenburg-Vorpommern, Saxony, Saxony-Anhalt and Thuringia. Slovenia celebrates it as well due to the profound contribution of the Reformation to that nation's cultural development, although Slovenes are mainly Roman Catholics. With the increasing influence of Protestantism in Latin America (particularly newer groups such as various Evangelical Protestants, Pentecostals or Charismatics), it has been declared a national holiday in Chile in 2009.