An optical device (44) includes three optical modulators, three optical modulator holders (447), a plurality of fluid circulating members (440), a cross dichroic prism (444), a fluid branching section (446), a fluid feed-in section (449) and a fluid pressurizing/feeding section (445). The three optical modulator holders (447) are fitted respectively to the three light-incident surfaces of the cross dichroic prism (444) through three supporting members (448). The fluid feed-in section (449) is fitted to the top surface of the cross dichroic prism (444). The fluid branching section (446) and the fluid pressurizing/feeding section (445) are laid one on the other and fitted to the lower surface of the cross dichroic prism (444).