The quadratic Frobenius test is a primality test. Some composite numbers may pass the test and such numbers are called quadratic Frobenius pseudoprimes. No quadratic Frobenius pseudoprimes with respect to x 2 + 5x + 5, which are congruent to 2 or 3 modulo 5, have been found. Shinohara studied a specific type of such a quadratic Frobenius pseudoprime, which is a product of distinct prime numbers p and q. He showed experimentally that p must be larger than 10 9 , if such a quadratic Frobenius pseudoprime exists. The present paper extends the lower bound of p to 10 11 .