Provided is a magnetic clamp device that reduces a magnetic flux leaking from a magnetic circuit passing through a permanent magnet and a magnetic pole member. The magnetic clamp device includes: a permanent magnet 20 surrounding a magnetic pole member 10 and disposed on a surface of a plate PL made of a magnetic body that magnetically clamps a mold in a magnetized state; and a reversible magnet 16 capable of reversing polarity and disposed at the rear of the permanent magnet 20. The magnetic pole member 10 is constituted by a plurality of magnetic pole pieces 101, 102, 103, and 104. Each of the magnetic pole pieces has a first lateral surface R with a shape corresponding to the opposite permanent magnet 20, and a second lateral surface T at which adjacent magnetic pole pieces oppose each other. The magnetic pole member 10 moves as the first lateral surfaces R are suction-adsorbed by the permanent magnet 20 without the second lateral surfaces T interfering with each other. The magnetic pole pieces 101, 102, 103, and 104 are held from the front and rear.