An image forming apparatus includes a first casing, a second casing, an arm, a guide unit, a support part, and an urging member. The second casing is supported on the first casing and configured to pivot relative to the first casing. The arm has a first end portion rotatably coupled to one of the first casing and the second casing and a second end portion slidably coupled to the other of the first casing and the second casing. The guide unit is provided at the other of the first casing and the second casing and configured to slidably guide a shaft. The guide unit includes a first guide and a second guide. The support part supports the first guide such that the first guide is movable toward and away from the second guide. The urging member is configured to urge the first guide toward the second guide.