An apparatus for manipulating magnetic particles includes a latch mechanism. The latch mechanism has a pivoting part provided on a door and an engaging part provided on a main body. In the apparatus for manipulating magnetic particles, a first contact portion of a latch engages with the engaging part at a contact point in a state that the door is closed. The contact point is located more outside of the main body than the pivot axis. Accordingly, in a case where an external force is applied to the door in a direction to open the door in a state that the door is closed, a force is applied from the engaging part to the first contact portion, thereby generating a rotational force in a C direction to the pivoting part. As a result, in the state that the door is closed, it is possible to suppress the door from being opened without a manipulation by the user.