The present invention addresses the problem of providing a safe and novel protein material which is useful in the prevention and treatment of various bone disorders such as osteoporosis, bone fractures, rheumatism, and arthritis when taken on a daily basis. The present invention also addresses the problem of providing bone-strengthening food and beverages or feed which is useful in the prevention and treatment of various bone disorders such as osteoporosis, bone fractures, rheumatism, and arthritis when taken orally. A protein material contains 2 to 15 mg/100 mg of angiogenin and/or an angiogenin degradation product, and cystatin and/or a cystatin degradation product at a mass ratio of 0.003 to 0.6 relative to the angiogenin and/or angiogenin degradation product. It is possible to strengthen bones and to prevent and treat various bone disorders such as osteoporosis, bone fractures, rheumatism, and arthritis by taking said protein material.