A stroke amount detection device includes a yoke, a magnetic flux generation section, and a magnetism detection section. The yoke has a protruding section that protrudes to outside the yoke. The magnetic flux generation section is located in the yoke. The magnetism detection section is disposed between the magnetic flux generation section and the protruding section. The magnetism detection section is disposed at a fixed position with respect to the magnetic flux generation section. The magnetism detection section outputs a signal in accordance with a magnetic flux density generated due to a relative movement of the yoke with respect to the magnetism detection section.