This creation is about a device for detecting reaction speed.Including: a body,It includes a light-emitting element and a control unit connected with the light-emitting element.A light detection area is formed by emitting a light through the light-emitting element.When the control unit detects the light emitted by the light-emitting element, it is defined as a first time point.When the control unit detects an object obscuring the light detection area, it is defined as a second time point.And the control unit calculates the time difference between the first time point and the second time point.So as to generate one of the reaction speed values of the object.本創作係有關一種偵測反應速度之裝置，包含有：一本體，包含有一發光元件及連接該發光元件的一控制單元，透過該發光元件發射一光線藉以形成一光線偵測區，該控制單元偵測該發光元件發出該光線時定義為一第一時間點，該控制單元偵測一物體遮蔽該光線偵測區時則定義為一第二時間點，又該控制單元計算該第一時間點及該第二時間點之間的時間差，藉以產生該物體之一反應速度值。
