A photocationically curable ink jet ink includes: a photoacid generator; a pigment; a monofunctional epoxy compound; a bifunctional epoxy compound; a monofunctional oxetane compound; and a bifunctional oxetane compound. In the photocationically curable ink jet ink, a concentration of the monofunctional epoxy compound is 20 wt % to 50 wt %, a concentration of the bifunctional epoxy compound is 20 wt % to 50 wt %, a concentration of the monofunctional oxetane compound is 5 wt % to 20 wt %, and a concentration of the bifunctional oxetane compound is 5 wt % to 20 wt %.