书写障碍（英语：Dysgraphia、Agraphia），又称失写症，是一种以手写字所产生的学习不利现象，跟阅读能力或是智力障碍无关。书写障碍者通常还是可以写字，但是缺乏某些精细动作技巧，例如胜任绑鞋带等任务有困难。有些人也缺乏基础的拼音技巧，例如对于英文本母p、q、b、d，以及中文注音符号的辨识有困难。在书面上作文时经常会写错字。问题会在在幼童时期逐渐接触书写时浮现，可能会出现不合适的字体大小跟空间配置，或者如果没有提醒的状况之下会写错或拼错字。

通常这类的书写障碍可能也会合并其他学习障碍，但不见得会有其他社交或是上课的问题。书写障碍也可能在妥瑞氏症、动作协调能力丧失症、注意力不足过动症或是如亚斯柏格等自闭症候群发生。

Dysgraphia is a deficiency in the ability to write, primarily handwriting, but also coherence. Dysgraphia is a transcription disability, meaning that it is a writing disorder associated with impaired handwriting, orthographic coding (orthography, the storing process of written words and processing the letters in those words), and finger sequencing (the movement of muscles required to write). It often overlaps with other learning disabilities such as speech impairment, attention deficit disorder, or developmental coordination disorder. In the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), dysgraphia is characterized as a learning disability in the category of written expression when one’s writing skills are below those expected given a person’s age measured through intelligence and age appropriate education. The DSM is not clear in whether or not writing refers only to the motor skills involved in writing, or if it also includes orthographic skills and spelling.