An undifferentiated stem cell removal agent is provided, containing at least one component selected from the group consisting of the following (a) to (d): (a) a cell that is capable of specifically inhibiting proliferation of a glypican-3-expressing cell; (b) a compound that is capable of specifically inhibiting proliferation of a glypican-3-expressing cell; (c) a cell that is capable of inducing a specific immune response against a glypican-3-expressing cell; and (d) a compound that is capable of inducing a specific immune response against a glypican-3-expressing cell.